You Do Need power plug adapter while traveling from Saint Vincent and the Grenadines to Nauru.

Here is Why You Need An Adapter

The outlet and plug type used in Nauru is I and in Saint Vincent and the Grenadines are A, B and G. This is how they look like.

Saint Vincent and the Grenadines

In Saint Vincent and the Grenadines, outlets of type A, B and G are in use.

Type A

Type B

Type G

Nauru

In Nauru, outlets of type I are in use.

Type I