Why can't the marine iguanas spend long periods of time playing and feeding in the ocean water?
they lose body temperature
they get too tired
they are not very good swimmers
they cannot withstand the salt

It is because they lose body temperature

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.