I caught my Uboat dancing like Shakira

[Sailor Steve]

Originally Posted by vanjast

Wouldn't the exact opposite effect these 2 options ?
When the DC explodes it creates a vacuum, which will then suck the uboat into it.

Just thinking!

No. If that were true then a torpedo against the hull of a ship would leave a hole that peeled out rather than in. The shock wave spreading out from the depth charge pushes the hull in if it's close enough, and pushes the boat away if the distance is greater.
http://en.wikipedia.org/wiki/Depth_charge

Note the section titled 'Underwater Explosions'.