Nayarit

Mexico

It is a rock inhabited by marine birds outside of the Bay and at the edge of the Pacific. It is surrounded by a rocky and sandy area with depths down to 160 feet. It's landmark is a 200 foot long sea cave formed by the action of waves through thousands of years leading from the south side all the way to the north side with depths of 90-130 in the deepest side. 
By definition (National Association for Cave Diving) there is one cavern zone on each side and a small cave area in the middle. Within this cave area , there is a small room where big amounts of red shrimp can be seen crawling on the granite walls. The rocky granite walls of El Morro are covered with invertebrates like sea fans, corals and sponges, as well as many species of crab, shrimp, nudibranchs, sea urchins and octopi. 
There are schools of jacks and batfish, spotted, green and zebra moray eels. All year round and with a little patience giant mantas will show themselves swimming around the divers bubbles. This is a site for experienced divers or advanced open water divers and is VISTITED AT ITS BEST WITH THE USE OF NITROX 32.

To penetrate and traverse the sea cave safely it is necessary to carry a minimum if 2 lights per person, be fully cavern trained and use cavern diving equipment. The other safe choice is to wear open water gear and one light per diver while conducting a tour by a guide with full cave training and in full cave gear.

El morro is located 5 miles West of Marietas Islands (60 to 80 minutes via fast boat).

El morro is also known as Morro.