Deep Navigation Colliery Deep Navigation Colliery Deep Navigation Colliery was a coal mine in South Wales, that operated from 1872 until 1991. Located next to the co-developed village of Treharris in the borough of Merthyr Tydfil, on development it was the deepest coalmine in South Wales Coalfield by some . Producing the highest quality steam coal, it powered both the Cunard passenger steamers RMS "Mauretania" and RMS "Lusitania" in their successful attempts at the Blue Riband prize for the most rapid Atlantic Ocean passage. The mine is also thought to have been one of several locally that provided coal to the RMS Titanic;
Submarine have used thick acrylic pressure hulls. The deepest deep-submergence vehicle (DSV) to date is "Trieste". On 5 October 1959, "Trieste" departed San Diego for Guam aboard the freighter "Santa Maria" to participate in "Project Nekton", a series of very deep dives in the Mariana Trench. On 23 January 1960, "Trieste" reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard (son of Auguste) and Lieutenant Don Walsh, USN. This was the first time a vessel, manned or unmanned, had reached the deepest point in the Earth's oceans. The onboard systems indicated