Put stone beneath my feet, though, and twice daily I'll watch the sea pull back and reveal its wondrous secrets. Below high tide on rocky shores you'll find an encyclopedia of creatures. Even more hospitable are those rare places where pools of sea water remain as the tide sinks lower. These wild aquariums can be full of exotic riches. Fantastically colored sea slugs, called nudibranchs, glide among swaying fronds of many-hued algae.
Tiny fish dart their manic missions.
Brilliantly colored, upside-down sea stars move deliberately and almost imperceptibly across overhanging boulders. My first guide to these alien worlds was my mother, Dr. Marilyn Harlin, now a marine biology professor at the University of Rhode Island. Because they're exposed so briefly, you have to observe them on their own terms. In return, you get to visit environments you'd otherwise have to wear scuba gear to witness. Tides, of course, lie at the heart of tide-pooling, and not all tides are equal.