You Do Need power plug adapter while traveling from El Salvador to Sint Eustatius.

Here is Why You Need An Adapter

The outlet and plug type used in Sint Eustatius are A, B, C and F and in El Salvador are A and B. This is how they look like.

El Salvador

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

Type A

Type B

Sint Eustatius

In Sint Eustatius, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F