A German U-boat scuppered off the coast of Kent in 1915 and a British A-class submarine which sank in 1912 off Dorset have been made protected historic wreck sites.
Anyone diving the wrecks will need a licence from Historic England.
Heritage Minister Tracey Crouch said the sites told an "important story about our past".
She said: "As we mark the centenary of the First World War, it is fitting that we remember the role of the wider war at sea and I am excited that these sites will be protected for years to come."
The A3 submarine was accidentally rammed in February 1912 by HMS Hazard while resurfacing off the Isle of Wight. It limped on before finally sinking off Lulworth.
It was later salvaged before being sunk again east of Portland where it was used as a gunnery target.
The U-8 was the first German submarine to be sunk in British waters when it was snared in anti-submarine nets off Folkestone.
Forced to surface, it was scuttled by the destroyers HMS Ghurka and HMS Maori and abandoned.
The crew survived and were marched through Dover to the castle.
One of the propellers, stolen by divers, was returned to the German navy after it was discovered being used as a coffee table. The second propeller is still missing.
Mark Dunkley, maritime designation adviser for Historic England, said: "The U-8 sits upright on the seabed in excellent condition and you can still see its periscopes and radio masts attached."
Two submarines which sank off the coast of England more than a century ago have been given protected status.