As a Costa Rican, you will not be allowed to enter Vietnam without a visa. Indeed, a Costa Rican needs a visa to travel to Vietnam.

There is no embassy of Vietnam in Costa Rica & it is quite hassle to apply for a visa by travelling to the location of the embassy of Vietnam in Countries Close to Costa Rica such as Panama, Cuba & Venezuela.

It is a good idea to apply online with a company in Vietnam to ask for arrangement for picking up your visa on arrival. There are many website providing service of consulting & supporting Costa Ricans get a visa to Vietnam, you just need to pick up a reliable one with cheap price.