The prevailing direction of the surface current within the reef lagoon and Chetumal Bay is southerly, and there are strong currents in the reef channels. Salinity in the reef lagoon averages 37.2 ppt and 40.9 ppt in the internal lagoons. Highest salinities are found in the supratidal ponds which 123.8 ppt. A thin freshwater lens lies 1-2.7 yards under the east coast ridge. Surface water stands in the supratidal flats for 8-9 months but disappear in the dry season when the water table drops approximately I yard.
Tidal fluctuations seen in some sinkholes suggest connections to the sea.
They can however, be much higher in inland savannas and supratidal flats in summer. The rest of the year has an average of 50 inches of rain with easterly but variable winds, and often a drier period in August. September, October and November are usually the months with most rainfall, although there are wide variations between years. Until May, winds tend to be strong and fairly constant, averaging 10- 15 miles per hour. There are numerous Mayan sites in the area.