The deepest point of the Indian Ocean lies in the:

The Java Trench, also called the Sunda Trench, lies in the north-eastern Indian Ocean, south of the Indonesian islands of Sumatra and Java. Its deepest part, sometimes called the Sunda Deep, is about 7,200 to 7,450 metres deep, making it the deepest point of the Indian Ocean.

Extent and formation:

• The trench runs in an arc about 3,000 km long, from near Myanmar and the Andaman Islands in the north-west, past Sumatra and Java, towards the Lesser Sunda Islands in the east.
• It is formed where the Indo-Australian Plate sinks beneath the Sunda Plate (part of the Eurasian Plate).

Effects:

• This plate boundary produces powerful earthquakes, such as the 2004 Sumatra-Andaman earthquake (magnitude 9.1), which triggered the devastating Indian Ocean tsunami.
• The sinking plate also feeds the chain of active volcanoes on Sumatra and Java, including Krakatoa, Merapi and Tambora.

Exploration:

In 2019, the explorer Victor Vescovo became the first person to reach the deepest point of the Java Trench in a crewed submersible, as part of the Five Deeps Expedition, which visited the deepest point of each ocean.

Deepest points of the five oceans:

• Pacific: Challenger Deep, Mariana Trench (about 10,900 to 11,000 m).
• Indian: Java (Sunda) Trench (about 7,200 m or more).
• Southern: South Sandwich Trench (about 7,400 m).
• Arctic: Molloy Deep (about 5,550 m).

Other features of the Indian Ocean floor:

• The Central Indian Ridge and the South-West and South-East Indian Ridges.
• The Ninety East Ridge, a long, straight underwater ridge.
• The Chagos-Laccadive Ridge, on which the Lakshadweep and Maldives islands stand.

Why not the other options?

• ✗The Mariana Trench and the Tonga Trench are in the Pacific Ocean.
• ✗The Puerto Rico Trench is in another ocean, covered in a separate question.