印度洋在古代稱為(wei)(wei)“厄(e)立特(te)里亞(ya)海(hai)”，早(zao)見(jian)于古希臘(la)地(di)理學(xue)家希羅多德（前484-前425年）所著(zhu)《歷史》一書及其編繪的世界(jie)地(di)圖中。“厄(e)里特(te)里亞(ya)”（ERYTHREA）希臘(la)文(wen)原意為(wei)(wei)紅色(se)，全名(ming)意為(wei)(wei)紅海(hai)。
“印度洋(yang)”這(zhe)一(yi)名稱相對出現得(de)較晚。公(gong)(gong)元(yuan)1世紀后期的羅(luo)馬地理學家彭波尼烏斯·梅拉可能是早使(shi)用此名的人。公(gong)(gong)元(yuan)10世紀，阿(a)拉伯(bo)人伊本·豪卡勒編繪的世界(jie)地圖上(shang)也(ye)使(shi)用了這(zhe)個名字。
近代(dai)正式使用印度洋一名則是在1515年左右，當時中歐地圖(tu)學家舍納爾編繪的地圖(tu)上(shang)，把(ba)這片大洋標注為“東(dong)方(fang)的印度洋”，此(ci)處的“東(dong)方(fang)”一詞是與(yu)大西(xi)洋相對而言的。
1497年(nian)，葡萄牙航海家達·伽(jia)馬東航尋找印度，便將沿(yan)途所經過的洋面(mian)統稱之為(wei)印度洋。
1570年奧爾太(tai)利烏斯編(bian)繪的世界地圖集中，把“東方(fang)的印度(du)洋(yang)”一名去(qu)掉“東方(fang)的”，簡(jian)化為“印度(du)洋(yang)”。這個名字逐漸被人們接受(shou)，成為通用的稱呼。
印(yin)度洋(yang)(yang)是聯(lian)系(xi)亞(ya)洲(zhou)、非(fei)洲(zhou)和大洋(yang)(yang)洲(zhou)之間的交通(tong)(tong)要(yao)道。從印(yin)度洋(yang)(yang)往(wang)西(xi)北(bei)通(tong)(tong)過(guo)曼德海峽(xia)、紅海；蘇伊士運河(he)、地中海和直布羅陀(tuo)海峽(xia)到達(da)西(xi)歐；向西(xi)南經(jing)好望(wang)角進入大西(xi)洋(yang)(yang)，通(tong)(tong)向歐美(mei)沿海各(ge)地；向東北(bei)經(jing)馬六甲(jia)海峽(xia)和龍目海峽(xia)進入太平洋(yang)(yang)。印(yin)度洋(yang)(yang)沿岸(an)是世界資源的一(yi)個重要(yao)出(chu)口地，沿岸(an)各(ge)國出(chu)口的石油、礦砂、橡膠、棉花、糧食和進口的水泥(ni)、機(ji)械產品和化工產品等(deng)大宗貨(huo)(huo)(huo)物都需要(yao)依靠廉(lian)價的海洋(yang)(yang)運輸(shu)(shu)，再加(jia)上大量(liang)的過(guo)境(jing)運輸(shu)(shu)，使印(yin)度洋(yang)(yang)有較(jiao)大的運輸(shu)(shu)量(liang)，擁有世界l/6的貨(huo)(huo)(huo)物吞(tun)吐量(liang)和近1/10的貨(huo)(huo)(huo)物周(zhou)轉量(liang)。
印(yin)(yin)度(du)(du)洋(yang)(yang)的(de)(de)(de)(de)航(hang)(hang)(hang)運(yun)業雖不(bu)如(ru)大西(xi)洋(yang)(yang)和太平洋(yang)(yang)發達，但由于中(zhong)東(dong)(dong)地區盛產的(de)(de)(de)(de)石(shi)(shi)油通過(guo)印(yin)(yin)度(du)(du)洋(yang)(yang)航(hang)(hang)(hang)線(xian)(xian)源(yuan)源(yuan)不(bu)斷(duan)向(xiang)外(wai)輸出(chu)，因(yin)而(er)印(yin)(yin)度(du)(du)洋(yang)(yang)航(hang)(hang)(hang)線(xian)(xian)在世(shi)(shi)界上(shang)占(zhan)有(you)重(zhong)要(yao)的(de)(de)(de)(de)地位(wei)(wei)。印(yin)(yin)度(du)(du)洋(yang)(yang)上(shang)運(yun)輸石(shi)(shi)油的(de)(de)(de)(de)航(hang)(hang)(hang)線(xian)(xian)有(you)兩條：一(yi)條是(shi)(shi)(shi)出(chu)波(bo)斯灣向(xiang)西(xi)，繞(rao)過(guo)南非的(de)(de)(de)(de)好望(wang)角(jiao)或(huo)者通過(guo)紅海(hai)(hai)(hai)(hai)(hai)、蘇伊(yi)士運(yun)河，到(dao)歐洲(zhou)和美國。這是(shi)(shi)(shi)世(shi)(shi)界上(shang)重(zhong)要(yao)的(de)(de)(de)(de)石(shi)(shi)油運(yun)輸線(xian)(xian)。一(yi)條是(shi)(shi)(shi)出(chu)波(bo)斯灣向(xiang)東(dong)(dong)，穿過(guo)馬六甲(jia)海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)或(huo)龍目海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)到(dao)日本和東(dong)(dong)亞(ya)其(qi)他國家。霍(huo)(huo)爾(er)木茲(zi)海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)在印(yin)(yin)度(du)(du)洋(yang)(yang)航(hang)(hang)(hang)線(xian)(xian)上(shang)占(zhan)有(you)重(zhong)要(yao)地位(wei)(wei)，波(bo)斯灣地區出(chu)口石(shi)(shi)油總(zong)量(liang)90%從此海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)運(yun)出(chu)，因(yin)而(er)霍(huo)(huo)爾(er)木茲(zi)海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)被稱為“石(shi)(shi)油海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)”。蘇伊(yi)士運(yun)河經馬六甲(jia)海(hai)(hai)(hai)(hai)(hai)峽(xia)(xia)的(de)(de)(de)(de)航(hang)(hang)(hang)線(xian)(xian)，是(shi)(shi)(shi)印(yin)(yin)度(du)(du)洋(yang)(yang)東(dong)(dong)西(xi)間一(yi)條重(zhong)要(yao)的(de)(de)(de)(de)航(hang)(hang)(hang)道，運(yun)輸量(liang)巨大，它將西(xi)歐、地中(zhong)海(hai)(hai)(hai)(hai)(hai)沿岸(an)各國的(de)(de)(de)(de)經濟(ji)與遠東(dong)(dong)及北美洲(zhou)西(xi)海(hai)(hai)(hai)(hai)(hai)岸(an)各國的(de)(de)(de)(de)經濟(ji)緊(jin)密地聯系起來。
印(yin)度洋(yang)的(de)地(di)理(li)位置非常(chang)重(zhong)要(yao)(yao)，是溝通亞(ya)洲、非洲、歐洲和大(da)(da)洋(yang)洲的(de)交通要(yao)(yao)道。向東通過馬六甲(jia)海(hai)峽可(ke)以進入(ru)太平洋(yang)，向西(xi)繞過好望角可(ke)達大(da)(da)西(xi)洋(yang)，向西(xi)北(bei)通過紅海(hai)、蘇伊士運河(he)，可(ke)入(ru)地(di)中海(hai)。航(hang)線(xian)主要(yao)(yao)由亞(ya)、歐航(hang)線(xian)和南(nan)亞(ya)、東南(nan)亞(ya)、南(nan)非、大(da)(da)洋(yang)洲之間的(de)航(hang)線(xian)。印(yin)度洋(yang)的(de)海(hai)底電纜(lan)多分(fen)布在北(bei)部，重(zhong)要(yao)(yao)的(de)線(xian)路有亞(ya)丁(ding)—孟買(mai)—馬德拉(la)斯(si)—新(xin)加坡線(xian)；亞(ya)丁(ding)—科倫坡線(xian)；東非沿岸(an)線(xian)。塞舌爾群島的(de)馬埃島、毛里求(qiu)斯(si)島和科科斯(si)群島是主要(yao)(yao)的(de)海(hai)底電纜(lan)樞紐(niu)站。沿岸(an)港(gang)口終年不(bu)凍，四季通航(hang)。
印度洋(yang)(yang)西(xi)南(nan)(nan)以通(tong)過南(nan)(nan)非(fei)厄加勒斯特的(de)經線同大西(xi)洋(yang)(yang)分界，東(dong)南(nan)(nan)以通(tong)過塔(ta)斯馬(ma)尼(ni)亞島東(dong)南(nan)(nan)角至南(nan)(nan)極(ji)大陸的(de)經線與太平洋(yang)(yang)聯結。印度洋(yang)(yang)的(de)輪廓為北部為陸地封閉，南(nan)(nan)面則以南(nan)(nan)緯60°為界，與南(nan)(nan)冰洋(yang)(yang)相連。
印度洋的主要屬海(hai)(hai)和海(hai)(hai)灣(wan)(wan)(wan)是紅海(hai)(hai)、阿拉伯海(hai)(hai)、亞(ya)丁(ding)灣(wan)(wan)(wan)、波斯灣(wan)(wan)(wan)、阿曼(man)灣(wan)(wan)(wan)、孟加拉灣(wan)(wan)(wan)、安達(da)曼(man)海(hai)(hai)、阿拉弗拉海(hai)(hai)、帝汶海(hai)(hai)、卡(ka)奔塔利(li)亞(ya)灣(wan)(wan)(wan)、大澳大利(li)亞(ya)灣(wan)(wan)(wan)、莫桑比克海(hai)(hai)峽(xia)等(deng)等(deng)。
印度(du)洋有(you)很多島(dao)(dao)(dao)(dao)嶼(yu)，其中(zhong)大部(bu)分是(shi)大陸島(dao)(dao)(dao)(dao)，如(ru)馬(ma)(ma)達加(jia)(jia)斯加(jia)(jia)島(dao)(dao)(dao)(dao)、斯里蘭卡島(dao)(dao)(dao)(dao)、安(an)達曼群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、尼科(ke)(ke)巴(ba)群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、明(ming)打威群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)等。留(liu)尼汪島(dao)(dao)(dao)(dao)、科(ke)(ke)摩羅群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、阿姆斯特丹島(dao)(dao)(dao)(dao)、克羅澤(ze)群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、凱(kai)爾(er)蓋(gai)朗群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)為火山(shan)島(dao)(dao)(dao)(dao)。拉(la)克沙(sha)群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、馬(ma)(ma)爾(er)代夫群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)、查戈斯群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)，以及爪哇(wa)西南的圣誕島(dao)(dao)(dao)(dao)、科(ke)(ke)科(ke)(ke)斯群(qun)(qun)(qun)島(dao)(dao)(dao)(dao)都是(shi)珊瑚島(dao)(dao)(dao)(dao)，馬(ma)(ma)達加(jia)(jia)斯加(jia)(jia)島(dao)(dao)(dao)(dao)是(shi)南回(hui)歸線穿過(guo)的島(dao)(dao)(dao)(dao)。
印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)底地貌錯綜(zong)復雜，除(chu)(chu)洋(yang)(yang)(yang)(yang)底中(zhong)(zhong)部有(you)呈“入”字形(xing)(xing)(xing)的(de)大(da)洋(yang)(yang)(yang)(yang)中(zhong)(zhong)脊外，東(dong)(dong)部尚(shang)有(you)東(dong)(dong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)和(he)(he)島(dao)(dao)(dao)弧、海(hai)(hai)(hai)(hai)(hai)(hai)溝帶，在(zai)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)、海(hai)(hai)(hai)(hai)(hai)(hai)丘、海(hai)(hai)(hai)(hai)(hai)(hai)臺之(zhi)間分布(bu)著許(xu)多(duo)海(hai)(hai)(hai)(hai)(hai)(hai)盆。印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)的(de)大(da)洋(yang)(yang)(yang)(yang)中(zhong)(zhong)脊，包括(kuo)中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)、阿(a)拉伯(bo)(bo)一(yi)(yi)(yi)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)、西南(nan)(nan)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)和(he)(he)東(dong)(dong)南(nan)(nan)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)。中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)°嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)從(cong)阿(a)姆斯特(te)(te)丹島(dao)(dao)(dao)向(xiang)(xiang)北(bei)延(yan)伸(shen)，一(yi)(yi)(yi)般高(gao)于(yu)(yu)兩側海(hai)(hai)(hai)(hai)(hai)(hai)盆1300-2500米(mi)(mi)(mi)，平均(jun)寬(kuan)度(du)(du)(du)(du)(du)達(da)800千(qian)米(mi)(mi)(mi)左右，由于(yu)(yu)被一(yi)(yi)(yi)些(xie)與(yu)之(zhi)垂直或斜交的(de)斷裂帶切(qie)斷錯開，中(zhong)(zhong)脊裂谷表(biao)現(xian)時斷時續(xu)的(de)特(te)(te)征，因此中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)形(xing)(xing)(xing)態崎嶇破(po)碎。中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)向(xiang)(xiang)西北(bei)延(yan)伸(shen)形(xing)(xing)(xing)成(cheng)阿(a)拉伯(bo)(bo)一(yi)(yi)(yi)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)，高(gao)度(du)(du)(du)(du)(du)較(jiao)(jiao)大(da)，繼續(xu)向(xiang)(xiang)西北(bei)延(yan)伸(shen)，進入亞丁灣和(he)(he)紅海(hai)(hai)(hai)(hai)(hai)(hai)；中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)從(cong)羅德里格(ge)斯島(dao)(dao)(dao)向(xiang)(xiang)西南(nan)(nan)分出(chu)西南(nan)(nan)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)，經(jing)愛(ai)德華太(tai)子群島(dao)(dao)(dao)，接(jie)大(da)西洋(yang)(yang)(yang)(yang)一(yi)(yi)(yi)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)；中(zhong)(zhong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)至圣波爾島(dao)(dao)(dao)向(xiang)(xiang)東(dong)(dong)南(nan)(nan)連(lian)接(jie)東(dong)(dong)南(nan)(nan)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)，再向(xiang)(xiang)東(dong)(dong)連(lian)接(jie)太(tai)平洋(yang)(yang)(yang)(yang)一(yi)(yi)(yi)南(nan)(nan)極(ji)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)和(he)(he)東(dong)(dong)太(tai)平洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)。印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)底除(chu)(chu)中(zhong)(zhong)脊海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)外，還有(you)許(xu)多(duo)近似南(nan)(nan)北(bei)向(xiang)(xiang)的(de)構造帶。這(zhe)些(xie)構造帶相互平行(xing)，綿延(yan)很遠，其中(zhong)(zhong)東(dong)(dong)印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)，走向(xiang)(xiang)與(yu)東(dong)(dong)經(jing)90°經(jing)線一(yi)(yi)(yi)致，是(shi)世界上(shang)較(jiao)(jiao)直的(de)一(yi)(yi)(yi)條(tiao)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)。它北(bei)起北(bei)緯10°附近的(de)安達(da)曼群島(dao)(dao)(dao)，南(nan)(nan)至南(nan)(nan)緯3l° 的(de)斷裂海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)，長約5 000千(qian)米(mi)(mi)(mi)，東(dong)(dong)西寬(kuan)約150-250千(qian)米(mi)(mi)(mi)。由于(yu)(yu)它沿著東(dong)(dong)經(jing)90°分布(bu)，故又叫東(dong)(dong)經(jing)90° 海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)或卡(ka)彭特(te)(te)海(hai)(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)(ling)。大(da)洋(yang)(yang)(yang)(yang)中(zhong)(zhong)脊呈“入”字形(xing)(xing)(xing)，將印(yin)(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)(yang)(yang)(yang)分成(cheng)三個海(hai)(hai)(hai)(hai)(hai)(hai)域(yu)。
印度(du)洋(yang)屬(shu)海(hai)(hai)(hai)(hai)較少(shao)。內海(hai)(hai)(hai)(hai)有(you)(you)(you)(you)(you)紅(hong)海(hai)(hai)(hai)(hai)和波斯灣(wan)；邊(bian)緣海(hai)(hai)(hai)(hai)有(you)(you)(you)(you)(you)西北(bei)部的(de)阿拉(la)伯海(hai)(hai)(hai)(hai)，東(dong)北(bei)部的(de)安(an)達曼(man)海(hai)(hai)(hai)(hai)，東(dong)部的(de)帝汶海(hai)(hai)(hai)(hai)和阿拉(la)弗拉(la)海(hai)(hai)(hai)(hai)；大(da)(da)海(hai)(hai)(hai)(hai)灣(wan)有(you)(you)(you)(you)(you)西北(bei)部的(de)亞丁灣(wan)和阿曼(man)灣(wan)，東(dong)北(bei)部的(de)孟加拉(la)灣(wan)，澳大(da)(da)利(li)亞北(bei)面(mian)的(de)卡奔塔利(li)亞灣(wan)（Carpentaria）、南面(mian)的(de)大(da)(da)澳大(da)(da)利(li)亞灣(wan)。在(zai)南極洲海(hai)(hai)(hai)(hai)域(yu)也有(you)(you)(you)(you)(you)一些屬(shu)海(hai)(hai)(hai)(hai)。海(hai)(hai)(hai)(hai)岸(an)線(xian)除北(bei)部比較曲折之外，大(da)(da)部分(fen)平直，少(shao)島(dao)嶼(yu)。大(da)(da)島(dao)有(you)(you)(you)(you)(you)馬(ma)達加斯加島(dao)、索科特拉(la)（Socotra）島(dao)、斯里蘭卡島(dao)，還有(you)(you)(you)(you)(you)塞席(xi)爾群(qun)島(dao)；火山(shan)島(dao)有(you)(you)(you)(you)(you)科摩羅（Comoros）群(qun)島(dao)、馬(ma)斯克(ke)林（Mascarene）群(qun)島(dao)和凱爾蓋朗（Kerguelen）群(qun)島(dao)；珊瑚島(dao)有(you)(you)(you)(you)(you)馬(ma)爾代(dai)夫(fu)群(qun)島(dao)。大(da)(da)陸(lu)(lu)邊(bian)緣地(di)帶包括(kuo)大(da)(da)陸(lu)(lu)棚和大(da)(da)陸(lu)(lu)坡。大(da)(da)陸(lu)(lu)棚一般比較狹窄，大(da)(da)陸(lu)(lu)棚較寬的(de)海(hai)(hai)(hai)(hai)域(yu)有(you)(you)(you)(you)(you)阿拉(la)伯海(hai)(hai)(hai)(hai)、安(an)達曼(man)海(hai)(hai)(hai)(hai)、孟加拉(la)灣(wan)和大(da)(da)澳大(da)(da)利(li)亞灣(wan)，寬處在(zai)澳大(da)(da)利(li)亞至新(xin)幾(ji)內亞島(dao)之間，約965千(qian)米。大(da)(da)陸(lu)(lu)坡陡峻之處坡度(du)10°-30°，一般坡度(du)較小。在(zai)印度(du)河、恒河入海(hai)(hai)(hai)(hai)口外的(de)海(hai)(hai)(hai)(hai)域(yu)，有(you)(you)(you)(you)(you)面(mian)積寬廣的(de)水(shui)下沖(chong)積扇，被(bei)水(shui)下峽谷所切割。
島(dao)(dao)(dao)(dao)(dao)弧帶(dai)從緬甸至(zhi)澳大(da)利(li)(li)亞延(yan)伸(shen)達(da)5150千(qian)(qian)(qian)米(mi)，可分為(wei)(wei)兩列(lie)平行的(de)(de)(de)(de)島(dao)(dao)(dao)(dao)(dao)鏈：內弧屬火(huo)山島(dao)(dao)(dao)(dao)(dao)，有(you)(you)大(da)、小(xiao)巽(xun)他群島(dao)(dao)(dao)(dao)(dao)（包括蘇(su)門答臘(la)島(dao)(dao)(dao)(dao)(dao)、爪(zhua)哇島(dao)(dao)(dao)(dao)(dao)、帝汶島(dao)(dao)(dao)(dao)(dao)等）；外(wai)弧為(wei)(wei)非火(huo)山島(dao)(dao)(dao)(dao)(dao)，有(you)(you)安達(da)曼群島(dao)(dao)(dao)(dao)(dao)、尼科(ke)巴（Nicobar）群島(dao)(dao)(dao)(dao)(dao)、明打威(wei)（Mentawai）群島(dao)(dao)(dao)(dao)(dao)等。島(dao)(dao)(dao)(dao)(dao)弧的(de)(de)(de)(de)外(wai)緣——爪(zhua)哇海(hai)(hai)(hai)(hai)(hai)溝為(wei)(wei)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)水域，深點7450米(mi)。印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)中(zhong)(zhong)央的(de)(de)(de)(de)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)可分為(wei)(wei)3支：北(bei)(bei)支為(wei)(wei)阿拉(la)伯——印(yin)(yin)(yin)度(du)(du)(du)(du)(du)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)；西(xi)(xi)(xi)南(nan)(nan)(nan)(nan)(nan)支為(wei)(wei)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)西(xi)(xi)(xi)南(nan)(nan)(nan)(nan)(nan)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)，它與大(da)西(xi)(xi)(xi)洋(yang)——印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)相連；東(dong)南(nan)(nan)(nan)(nan)(nan)支為(wei)(wei)中(zhong)(zhong)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)，它與印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)東(dong)南(nan)(nan)(nan)(nan)(nan)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)相接(jie)。北(bei)(bei)支海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)和(he)西(xi)(xi)(xi)南(nan)(nan)(nan)(nan)(nan)支海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)是(shi)(shi)結構復(fu)雜的(de)(de)(de)(de)海(hai)(hai)(hai)(hai)(hai)底山脈，寬(kuan)度(du)(du)(du)(du)(du)400-970千(qian)(qian)(qian)米(mi)，相對(dui)高度(du)(du)(du)(du)(du)1830-3050米(mi)，海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)的(de)(de)(de)(de)中(zhong)(zhong)脊為(wei)(wei)裂谷帶(dai)，地貌極為(wei)(wei)崎嶇險峻；東(dong)南(nan)(nan)(nan)(nan)(nan)支海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)從中(zhong)(zhong)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)至(zhi)阿姆斯特丹島(dao)(dao)(dao)(dao)(dao)的(de)(de)(de)(de)寬(kuan)度(du)(du)(du)(du)(du)達(da)1450千(qian)(qian)(qian)米(mi)，裂谷很少(shao)。印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)中(zhong)(zhong)央的(de)(de)(de)(de)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)被大(da)小(xiao)不一的(de)(de)(de)(de)斷(duan)裂帶(dai)所(suo)切割，例如歐文(wen)斷(duan)裂帶(dai)，即延(yan)伸(shen)至(zhi)阿拉(la)伯海(hai)(hai)(hai)(hai)(hai)盆(pen)和(he)索(suo)馬(ma)利(li)(li)海(hai)(hai)(hai)(hai)(hai)盆(pen)，海(hai)(hai)(hai)(hai)(hai)底巖層位(wei)移達(da)320千(qian)(qian)(qian)米(mi)。印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)東(dong)部(bu)海(hai)(hai)(hai)(hai)(hai)域1962年發現(xian)的(de)(de)(de)(de)東(dong)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)（或稱「東(dong)經九十(shi)度(du)(du)(du)(du)(du)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)」），南(nan)(nan)(nan)(nan)(nan)北(bei)(bei)直線(xian)延(yan)伸(shen)約(yue)4990千(qian)(qian)(qian)米(mi)，為(wei)(wei)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)中(zhong)(zhong)較長(chang)較直的(de)(de)(de)(de)海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)。海(hai)(hai)(hai)(hai)(hai)嶺(ling)(ling)(ling)(ling)之間為(wei)(wei)一系列(lie)海(hai)(hai)(hai)(hai)(hai)盆(pen)︰北(bei)(bei)部(bu)和(he)西(xi)(xi)(xi)北(bei)(bei)部(bu)有(you)(you)阿拉(la)伯海(hai)(hai)(hai)(hai)(hai)盆(pen)、索(suo)馬(ma)利(li)(li)海(hai)(hai)(hai)(hai)(hai)盆(pen)；中(zhong)(zhong)部(bu)自西(xi)(xi)(xi)而(er)東(dong)，有(you)(you)馬(ma)達(da)加斯加海(hai)(hai)(hai)(hai)(hai)盆(pen)、中(zhong)(zhong)印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)海(hai)(hai)(hai)(hai)(hai)盆(pen)、科(ke)科(ke)斯海(hai)(hai)(hai)(hai)(hai)盆(pen)和(he)北(bei)(bei)澳大(da)利(li)(li)亞海(hai)(hai)(hai)(hai)(hai)盆(pen)；南(nan)(nan)(nan)(nan)(nan)部(bu)重要的(de)(de)(de)(de)是(shi)(shi)克羅(luo)澤(ze)（Crozet）海(hai)(hai)(hai)(hai)(hai)盆(pen)。根(gen)據大(da)陸漂移學說，印(yin)(yin)(yin)度(du)(du)(du)(du)(du)洋(yang)是(shi)(shi)在(zai)中(zhong)(zhong)生代（距(ju)今6500萬-22500萬年前）南(nan)(nan)(nan)(nan)(nan)半球貢(gong)德瓦(wa)納古陸解體時，印(yin)(yin)(yin)度(du)(du)(du)(du)(du)、澳大(da)利(li)(li)亞大(da)陸、南(nan)(nan)(nan)(nan)(nan)極大(da)陸、非洲(zhou)大(da)陸和(he)南(nan)(nan)(nan)(nan)(nan)美大(da)陸的(de)(de)(de)(de)漂移而(er)形(xing)成的(de)(de)(de)(de)。
