Each door has a window, through which you catch glimpses of sunlight. In order, the nearest doors are labelled "California Seashore Habitat," "Arctic Ocean," "Temperate New England Sea Shore," and "Tropical Key Waters."
Moving shadows on the windows indicate the flight of sea birds. You can hear, faintly, the mewing of seagulls and the crashing of the surf.
As much as you wouldn't mind exploring, you know you should go back.