Currents and Tides - Generally in the western Caribbean, surface currents tend in a northerly direction. This northerly current creates a thin southerly counter current directly in front of the barrier reef and around the atolls of Belize (Surface Current Map).

Between the barrier reef and the mainland, the currents tend in a southerly direction. The emptying of the many coastal rivers and the push of the Tradewinds creates a head of water which is funneled to the south and out southern edge of the reefs.

By far the strongest currents are generated by the tides. Though tidal range is small (seldom greater than 18 inches), the numerous cuts through the barrier reef can restrict the flow of water and cause strong local and temporal currents of up to 1.5 kts. These breaks in the barrier reef are wonderful habitats for large fish and rich coral growth.

Bathymetry - The general seafloor profile of the coastal waters in Belize leads from the inland lagoons and beaches of the shoreline to the lagoon, barrier platform, barrier reef and wall and finally the coral atolls (X-Section of Continental Shelf).

The inner lagoon consist mainly of sediments from river run off. Seagrass and hardy corals abound, and fishing at the river mouths is spectacular. Snorkeling offshore is OK at best. Often, the water is murky from the rivers.

Moving east, the lagoon abruptly rises to the barrier platform, a plateau of seagrass beds, coral sand islands and patch reefs. The barrier platform varies in width and composition from north to south. For example, north of Belize City, the barrier platform is narrow, sometimes disappearing all together. South of Belize City, the platform widens to almost 6 miles. South of Blue Ground Range, the platform topography reaches its maximum complexity with a narrow outer platform; an area of drowned reefs, patch reefs and islands; and a deepening lagoon.

The furthest south island in this complex area of this barrier platform/lagoon mix is Laughing Bird Caye, a small island which perches atop a formation called a faroe (see below). The Snake Cays and the Cayes of the Port Honduras Area are the furthest south islands in the inner lagoon. South of Gladden Spit, the outer platform narrows to about 1 mile, with wide passes through the barrier reef . The barrier platform ends in a hook shape at the Sapodilla Cays.

The barrier platform is bordered on the east by the barrier reef, a wall of coral which frequently breaks the surface of the Caribbean Sea. The barrier reef crest slopes to the east to the edge of the continental shelf, where in numerous places vertical walls drop out of sight.

Temperatures and Visibility - Water temperatures are fairly constant all year lying between the mid to high 70's to the low 80's. A lightweight dive "skin" or a 1/16 inch "shorty" wetsuit should be perfect for multiple dive days.

Because the barrier reef and the majority of the great dive spots lie so far from shore, visibility is not affected by rain runoff. Visibility normally ranges between 50 - 150 feet. During "northers" - cold fronts which hit Belize during the winter months - visibility can be reduced for days at a time.

While diving and exploring the underwater world of Belize, you will encounter a number of different reef types. These include fringing reefs, patch reefs, faroes, barrier reefs, and atolls.

Fringing Reefs - Fringing reefs are typically found close to mainland shores. The only fringing reef in Belize is found at Rocky Point on the northern end of Ambergris Caye. The reef actually rises out of the water at Rocky Point and you can walk among coral skeletons embedded in the shoreline rocks. The Belize fringing reefs show little zonation of corals, consisting mainly of the huge star coral or Montastrea sp. Snorkeling to the north of Rocky Point is good among the patch reefs behind the barrier reef.

Patch Reefs - Patch reefs range from small clumps of coral to huge, sprawling reefs. They are widespread throughout the coastal zone, though more abundant in the south, especially in the complex barrier platform region south of Southwater caye. The larger patch reefs show distinct zonation of corals with the seaward facing sides supporting Montastrea and A. palmata (elkhorn coral) and the leeward slopes covered by thickets of A. cervicornis (staghorn coral). Mexico Rocks (shown to right) off of Ambergris Caye is an excellent example of a well developed patch reef.

Faroe - A faroe is a ringed reef or angular atoll on a continental shelf, also known as a shelf atoll. Like an atoll, a faroe is steep sided and encloses a central lagoon. The best example of a faroe in Belize is Laughing Bird Caye. Most ringed reefs in Belize can be divided into three main areas: 1) the outer rim; 2) the inner lagoon; 3) and inner patch reefs. Other types of minor habitats include mounds, spits and mangrove islands. Each of these areas support different types of marine life.

Barrier Reef - The Belize Barrier Reef is a nearly continuous wall of coral for almost 140 miles from Mexico in the north to the Sapodilla Cayes in the south. The best developed sections of the barrier reef are south of Columbus Reef east of Dangriga.

The barrier reef region has been heavily studied and has been shown to possess distinct zones from the lagoon seaward to the drop off. Directly landward of the barrier reef lies the back reef lagoon, characterized by hardy corals and seagrass beds. The reef crest breaks the surface of the water and bears the brunt of the heavy surf. Directly eastward of the barrier reef lies the fore reef, rich with elkhorn and star corals which form massive canyons called spur and grooves. The forereef continues to slope eastward to the reef wall, which drops vertically into the depths. The spur and groove forereef and drop off provides the most spectacular diving in Belize (Generalized Reef Zonation Profile).

Coral Atolls - The final reef type, seaward of the continental shelf is composed of the three coral atolls. The three Belizean atolls have been described as "the finest structures of their type in the Caribbean Sea".

Turneffe Islands, the largest of the atolls, has a maximum length of 30 miles and varies in width up to a maximum of 10 miles. Numerous mangrove covered sand cays, in a variety of sizes, rim Turneffe. The interior of the atoll is carpeted with vast meadows of seagrass. Diving is excellent off the southern tip of the atoll.

Lighthouse Reef has an overall length of 25 miles and a width of approximately 4.5 miles with an area of over 78 sq.mi.. Lighthouse Reef is the smallest of the three atolls. This atoll is surrounded by a well developed reef-rim with only three major gaps. Halfmoon Cay Natural Monument lies along the southeastern portion of the reef and the Blue Hole Protected area lies within the interior of the atoll. Lighthouse Reef supports a remarkable diversity of living reef and reef-flat areas, well developed spur and groove zones, and a unique arc shaped reef segment which lies on the southwest corner of the reef.

The greatest length of Glover's Reef is 15 miles and its greatest width is 6.5 miles. The approximate area of over 80 sq.mi.. makes it slightly larger than Lighthouse Reef but much smaller than Turneffe Island. This atoll is surrounded by broad, well-defined reefs of living coral breaking the surface.