You Do Need power plug adapter while traveling from British Virgin Islands to Belize.

Here is Why You Need An Adapter

The outlet and plug type used in Belize are A, B and G and in British Virgin Islands are A and B. This is how they look like.

British Virgin Islands

In British Virgin Islands, outlets of type A and B are in use.

Type A

Type B

Belize

In Belize, outlets of type A, B and G are in use.

Type A

Type B

Type G