While patrolling the beach one evening (12am-4am) a group of volunteers and I just opted to stay up being that an Arribada in Ostional had just begun. Arribada means "The Arrival" and in Ostional it is when thousands of sea turtle mothers come on shore and lay their eggs. Before my arrival in Costa Rica I had no idea this type of event was even possible. Absolutely unknown to most, but easily the most amazing thing I have ever experienced.