http://imgur.com/a/XbxMm
Grid 022086 as seen in the 2nd picture.

Just like on a beach, I should easily be able to transition from swimming to walking when swimming into the ramp, but the character is stuck the way it is in the picture, and forced to swim around to get on land.

I have not tested this with other underwater ramps, it is not unlikely to be an issue with all underwater ramps in arma 3.