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

Here is Why You Need An Adapter

The outlet and plug type used in Cayman Islands are A and B and in Sierra Leone are D and G. This is how they look like.

Sierra Leone

In Sierra Leone, outlets of type D and G are in use.

Type D

Type G

Cayman Islands

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

Type A

Type B