You Do Need power plug adapter while traveling from Bahrain 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 Bahrain is G. This is how they look like.

Bahrain

In Bahrain, outlets of type G are in use.

Type G

Costa Rica

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

Type A

Type B