Level
3rd
Casting Time
1 Action
Ritual
Range/Area
30 ft
Components
V, S, M *
Duration
1 Hour
School
Transmutation
Attack/Save
None
Damage/Effect
Movement
This spell grants the ability to move across any liquid surface—such as water, acid, mud, snow, quicksand, or lava—as if it were harmless solid ground (creatures crossing molten lava can still take damage from the heat). Up to ten willing creatures of your choice within range gain this ability for the duration.
An affected target must take a Bonus Action to pass from the liquid’s surface into the liquid itself and vice versa, but if the target falls into the liquid, the target passes through the surface into the liquid below.
* - (a piece of cork)
"An affected target must take a Bonus Action to pass from the liquid’s surface into the liquid itself and vice versa, but if the target falls into the liquid, the target passes through the surface into the liquid below."
So, if you fall unconscious into a body of water, you are unable to come back to the surface because it requires a Bonus Action, which you can't take because you're unconscious. Falling into any body of water while unable to take a BA guarantees that you drown.