You Do Need power plug adapter while traveling from Ireland (Eire) to Costa Rica.

Here is Why You Need An Adapter

The outlet and plug type used in Costa Rica are A and B and in Ireland (Eire) is G. This is how they look like.

In Ireland (Eire), outlets of type G are in use.

Type G

In Costa Rica, outlets of type A and B are in use.

Type A

Type B

I am from

going to