To give some examples of todays submarine capabilities check out the following data;
World War II German U-boats had estimated collapse depths of 200 to 280 metres or 660 to 920 feet.
Collapse Depth of a Type XXIII U-Boat is 180 meters or 591 feet with a max speed of 9.7 knots surfaced and 12.5 knots submerged.
Submarines of the 60s - 70s
America - Test Depth of a Permit class submarine is 400 meters or 1300 feet with a max speed of 15 knots surfaced and 28 knots submerged.
Modern nuclear attack submarines are estimated to have a test depth of 490 meters or 1600 feet, which would imply a collapse depth of 730 meters or 2400 feet.
Britain - Test Depth of an Astute class submarine is 300+ meters or 984+ feet with a max speed of 18 knots surfaced and 29+ knots submerged.
Britain - Maximum Operating Depth of a Trafalgar class submarine is 600 meters or 1968 feet with a max speed of 20 knots surfaced and 32 knots submerged.
Britain - Maximum Operating Depth of a Vanguard class submarine is X meters or X feet with an estimated max speed of 20 knots surfaced and 25 knots submerged.
Russia - Test Depth of a Typhoon class submarine is 400 meters or 1300 feet with a max speed of 22.22 knots surfaced and 27 knots submerged.
Russia - Test Depth of a Borei class submarine is 450 meters or 1476 feet with a max speed of 15 knots surfaced and 29 knots submerged.
France - Test Depth of a Triomphant class submarine is 400 meters or 1300 feet with a max speed of 25+ knots.
America - Test Depth of a Ohio class submarine is 240+ meters or 800+ feet with a max speed of 12 knots surfaced and 20-25 knots submerged.