Empire Relic

SS Empire Heritage

That's a military war machine, a tank. Going by the amount of crud covering it looks like it has been down there a while. Given that we can see color and the background isn't totally black, it might not be too deep. Plus we have a SCUBA diver, but that isn't a good indicator because SCUBA divers can go very deep with special equipment. This picture sparked my interest, so I did a little checking. The tank was cargo on the Empire Heritage, which had a string of bad luck.

Empire Heritage, a 15,702 GRT tanker, was launched in 1930, hit a mine in  January 1941 and beached. Refloated in March 1941 and beached, but broke in two and declared a total loss. To MoWT, repaired and renamed Empire Heritage. Torpedoed September 1944 and sunk by U-482. - paraphrased from Wikipedia

MoWT is the Ministry of War Transport. Empire Heritage was one of about a zillion Empire ships:

An Empire ship is a merchant ship that was given a name beginning with "Empire" in the service of the Government of the United Kingdom during and after World War II.
. . .
New Empire ship construction represented an enormous undertaking that included classes of freighters, tankers, aircraft carriers, fast cargo liners, tank landing ships, Deep Sea Salvage and Rescue Tugs and several other categories. Total production numbered in the hundreds.
Empire ships were supplements to Britain's normal peacetime merchant fleet, swelling its wartime numbers to 12,000, then the largest merchant ship fleet in the world. Approximately 4,000 ships on the British register were lost between 1939 and 1945, a considerable number being sunk during the Battle of the Atlantic. - Wikipedia

Via Knuckledraggin My Life Away