I recently went kayaking and can't get my head around the physics going on in the situation I experienced. I'll try explain it as best as I can. The kayak is hollow and is basically a shell. A kayak is flipped while on the surface of a water, so I was still sitting inside it but now under water. I then fell out of the sitting position while under water and then swam to the surface to turn the kayak back over to the upright normal position. When trying to turn the kayak back over it is difficult because there appears to be an air pressure seal between the water and the place where the person sits, because the kayak is still full of air. So it takes more force to turn it back over. Where is the best place to push the kayak to break this seal, at the ends or towards the middle and should I push at an angle or straight up? What are the physics principles at work here?