You Do Need power plug adapter while traveling from Tuvalu 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 Tuvalu is I. This is how they look like.

Tuvalu

In Tuvalu, outlets of type I are in use.

Type I

Sint Eustatius

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

Type A

Type B

Type C

Type F