Underwater, these towers shape a rugged, interesting environment for scuba divers, and over time the elements have created caves, overhangs. and swim-throughs in this soft rock. Some caves penetrate the rock as much as 30 meters or more which make exciting explorations.

Other types of environments include vertical walls that plunge from the surface to over 25 meters. On these walls grow a profusion of soft corals, large orange sea fans, black coral and long stringy sea whips. Several types of unusual coral trees grow in the waters surrounding Phi Phi including a white coral bush that looks like a frocked Christmas tree and is covered with ornament-like growth in the form of oysters and crinoids.

In many places, the islands are fringed with hard-coral gardens home to a wide assortment of radiant tropical creatures. In most areas coral growth and marine life including five species of anemone fish is profuse and most but not all of the same fish spaces that inhabit the Similans can be found around Ko Phi Phi as well.