1 - Jump into water with Strider with vertical or inverted / on the front (see video)
2 - Additionaly, with this script function, you can make it drive really better (not in the video).
(vehicle player) setPos [getPos (vehicle player) select 0, getPos (vehicle player) select 1, (getPos (vehicle player) select 2)+1];
(vehicle player) setVectorUp surfaceNormal position (vehicle player);