You Do Need power plug adapter while traveling from Cocos (Keeling) Islands to Nicaragua.

Here is Why You Need An Adapter

The outlet and plug type used in Nicaragua are A and B and in Cocos (Keeling) Islands is I. This is how they look like.

Cocos (Keeling) Islands

In Cocos (Keeling) Islands, outlets of type I are in use.

Type I

Nicaragua

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

Type A

Type B