You Do Need power plug adapter while traveling from United States Virgin Islands to Niue.

Here is Why You Need An Adapter

The outlet and plug type used in Niue is I and in United States Virgin Islands are A and B. This is how they look like.

United States Virgin Islands

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

Type A

Type B

Niue

In Niue, outlets of type I are in use.

Type I