The Mariana Trench is named after which nearby island group?

The Mariana Trench is named after the Mariana Islands.

The Mariana Islands form a crescent-shaped volcanic archipelago in the northwestern Pacific, east of the Philippines and south-southeast of Japan. The trench lies roughly 200 kilometres to the east of the island chain, so its name identifies the nearby islands rather than a Greek, geological or oceanographic figure.

The islands themselves were named Las Marianas in honour of Mariana of Austria, the Spanish queen consort of King Philip IV. Spanish colonization in the seventeenth century established the name, which later became attached to the trench and the surrounding geological arc.

The archipelago contains fifteen principal volcanic islands and is politically divided between Guam, a United States territory, and the Commonwealth of the Northern Mariana Islands. The islands and trench are part of the Izu–Bonin–Mariana arc system, created by the Pacific Plate descending beneath the Mariana Plate. That same subduction process formed both the volcanic island chain and the nearby oceanic trench.