Energy from the oceans can be obtained in the form of tidal energy, wave energy and ocean thermal energy. But these energy sources suffer from the following limitations:
1. There are very few locations where dams to utilise tidal energy can be built.
2. Cost of installation of power houses is extremely high and efficiency of plants is comparatively small.
3. Power plants built in oceans or at sea shores will need high continuous maintenance as chances of corrosion are extremely high.