You Do Need power plug adapter while traveling from Maldives to Tonga.

Here is Why You Need An Adapter

The outlet and plug type used in Tonga is I and in Maldives are C, D, G, J, K and L. This is how they look like.

Maldives

In Maldives, outlets of type C, D, G, J, K and L are in use.

Type C

Type D

Type G

Type J

Type K

Type L

Tonga

In Tonga, outlets of type I are in use.

Type I