[something]

i don't think surface tension is doing anything for something the size of a human, or a stone for that matter. if it was surface tension, why does it care that something is moving?

it probably has more todo with the water you are displacing having enough inertia that it can't get out of your way fast enough. it stays there long enough to deflect your path upward, keeping you up.

you sink when you pierce the surface because of the massive drag you introduce. it slows you down very quickly so you sink.