Where is the blue key card?

Hint 1 of 4:

The blue key card will open a door that's underwater, not far from that big,
neon lounge sign.

Hint 2 of 4:

Not far from there, you can find an opening in the rock.

Hint 3 of 4:

Swim up through that opening, and jump around on the rocks.

Hint 4 of 4:

You'll find the blue card up there.