You Do Need power plug adapter while traveling from Cayman Islands to Cuba.

Here is Why You Need An Adapter

The outlet and plug type used in Cuba are A, B, C and L and in Cayman Islands are A and B. This is how they look like.

Cayman Islands

In Cayman Islands, outlets of type A and B are in use.

Type A

Type B

Cuba

In Cuba, outlets of type A, B, C and L are in use.

Type A

Type B

Type C

Type L