The USS Johnston was sunk in the Battle off Samar in World War II. Its wreck descended into the Philippine Trench, the third deepest trench in the world, and we know of no deeper wrecks.
I’ve written a bit about the Battle off Samar before – and the notorious message “the world wonders.” A small cluster of American ships were under attack by a huge Japanese fleet. One of those ships was the USS Johnston.
The American ships were hopelessly outmatched. The American task unit had three destroyers (including the USS Johnston), four destroyer escorts, and eight escort carriers; the Japanese fleet bearing down on them included four battleships, eleven destroyers, and six heavy cruisers. Despite this, the US destroyer dropped a smokescreen and charged directly into the fray. It was hit, of course, and sunk just after 10am that morning.
This battle took place above the Philippine Trench. It’s the third deepest in the world, behind the Mariana Trench (10,984 metres) and the Tonga Trench (10,800 metres). The ship did not sink all the way to the deepest point in the trench, of course, but a couple of months ago – in October of this year – a wreck was found at 6,220 metres. That wreck is thought to be the remains of the USS Johnston.
For reference, the wreck of the Titanic is 3,700 metres deep, in that region of the ocean termed the abyssopelagic zone – named for the abyss. This wreck is two and a half kilometres deeper, in the hadopelagic – named for Hades.
[Thanks to Neal Agarwal’s The Deep Sea for drawing my attention to this topic.]