When riding a boat in flowing water, both moving toward snow layers, once the boat makes contact with the snow, the player begins to move downward into the ground in a glitchy manner. Once the player's head goes under the ground, it teleports the player back up to the normal riding position, and starts moving downward again.

Once you exit the boat, it sinks through the ground and rests one block underground.

It is currently unknown to me whether this only works when riding diagonally into the snow, or perpendicular as well. Also, I do not know if this glitch happens in Survival mode, as I was in creative when I found it.

This occurred in Singleplayer, 1.19

An example of this is shown in the attachment below. (I cut the video to fit the file size, that isn't another glitch :okHand

Thanks for your time!