We studied the oceanographic and meteorological conditions in four sites related to national parks in the Área de Conservación Guanacaste. Variables such as temperature, salinity and dissolved oxygen were studied through the water column in at least one tidal cycle at three bays Tamarindo, Culebra, Santa Elena located in the North Pacific of Costa Rica, and in Ballena Bay, off the Gulf of Nicoya. At the same time, local wind and ocean currents were measured in order to evaluate the dynamic forces at these sites. Environmental variables around Costa Rica were consulted from operational data sources, such as ocean currents and surface wind patterns, to know the prevailing conditions and their influence. During strong trade winds, a typical dry season condition, strong ocean currents are generated in front of the Nicoya Peninsula. This is consistent with the prevailing oceanographic conditions offshore Papagayo Gulf when the wind jet is established. These external forces influence the ocean circulation of open water bays, as was observed in Tamarindo Bay. The local wind and tide are components that modulate local circulation, especially in closed bays like Santa Elena and Ballena. The stratified current structure of the water layers in Ballena Bay showed a typical estuarine condition with the presence of different thermohaline fields dominated by tidal forces. Rev. Biol. Trop. 62 (Suppl. 4): 17-31. Epub 2014 Diciembre 01.

Keywords: atmospheric dynamic, sea temperature, dissolved oxygen, estuarine circulation, Área de Conservación Guanacaste.