You Do Need power plug adapter while traveling from New Zealand to Sint Maarten.

Here is Why You Need An Adapter

The outlet and plug type used in Sint Maarten are A and B and in New Zealand is I. This is how they look like.

New Zealand

In New Zealand, outlets of type I are in use.

Type I

Sint Maarten

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

Type A

Type B