You Do Need power plug adapter while traveling from Saint Martin 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 Saint Martin are C and E. This is how they look like.

Saint Martin

In Saint Martin, outlets of type C and E are in use.

Type C

Type E

Sint Maarten

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

Type A

Type B