You Do Need power plug adapter while traveling from New Caledonia to Saint Lucia.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Lucia is G and in New Caledonia are C and F. This is how they look like.

New Caledonia

In New Caledonia, outlets of type C and F are in use.

Type C

Type F

Saint Lucia

In Saint Lucia, outlets of type G are in use.

Type G