The submersible pump should always be below the water level as the water is used to cool the pump. The pump can get overheated if the water level falls or if the pump is operated out of the water.
Submersible pumps should never be used in water where people may swim. There is a risk of electricity leaking and people may get electrocuted.
Advantages of submersible pumps over jet pumps.
Submersible pumps are more efficient.
They do not require priming
They are quieter.
They do not require any extra space.
Disadvantages of submersible pumps
High initial cost
Risk of current leakage in water