The answer is Ocean.
Oceans are larger than ponds and or an aquarium. Hence they possess wider exposed surface with more number of free surface molecules.Greater the number of surface molecules, greater number of molecules may escape from the surface easily..and hence greater will be the rate of evaporation.
The rate of evaporation depends even on the external climatic conditions such as Temperature, Wind, Pressure etc.
Higher the temperature. higher will be the rate of evaporation.