Undertow

You Create a puddle of water on the ground. The puddle is connected to an Invisible 3-foot-by-5-foot portal that opens to an extradimensional space lasting until the spell ends. That space can be reached by choosing to sink into the puddle, which can be climbed out of with 5ft of movement.

The space can hold up to eight Medium or smaller creatures. Attacks, spells, and other effects can’t pass into or out of the space, but creatures inside it can see through the portal. Anything inside the space appears outside the portal when the spell ends.