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

Here is Why You Need An Adapter

The outlet and plug type used in Vanuatu 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

Vanuatu

In Vanuatu, outlets of type I are in use.

Type I