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. These breaks in the barrier reef are wonderful habitats for large fish and rich coral growth. 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.