Formations

• Fringing reef – a reef that is directly attached to a shore or borders it with an intervening shallow channel or lagoon.
• Barrier reef – a reef separated from a mainland or island shore by a deep lagoon (see Great Barrier Reef).
• Patch reef – an isolated, often circular reef, usually within a lagoon or embayment.
• Apron reef – a short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore.
• Bank reef – a linear or semi-circular shaped-outline, larger than a patch reef.
• Ribbon reef – a long, narrow, somewhat winding reef, usually associated with an atoll lagoon.
• Atoll reef – a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island; see atoll.
• Table reef – an isolated reef, approaching an atoll type, but without a lagoon.

Distribution

Coral reefs are either restricted or absent from the west coast of the Americas, as well as the west coast of Africa. This is due primarily to upwelling and strong cold coastal currents that reduce water temperatures in these areas.Nybakken, James. 1997. Marine Biology: An Ecological Approach. 4th ed. Menlo Park, CA: Addison Wesley. Corals are also restricted from off the coastline of South Asia from Pakistan to Bangladesh. They are also restricted along the coast around north-eastern South America and Bangladesh due to the release of vast quantities of freshwater from the Amazon and Ganges Rivers respectively.Fact: date=December 2007

Famous coral reefs and reef areas of the world include:

• The Great Barrier Reef - largest coral reef system in the world, Queensland, Australia;
• The Belize Barrier Reef - second largest in the world, stretching from southern Quintana Roo, Mexico and all along the coast of Belize down to the Bay Islands of Honduras.
• The New Caledonia Barrier Reef - second longest double barrier reef in the world, with a length of about 1500km.
• The Andros, Bahamas Barrier Reef - third largest in the world, following along the east coast of Andros Island, Bahamas between Andros and Nassau.
• The Red Sea Coral Reef - located off the coast of Egypt and Saudi Arabia.
• Pulley Ridge - deepest photosynthetic coral reef, Florida
• Many of the numerous reefs found scattered over the Maldives