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

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea are C and E 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

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E