I found this beautiful False Coral Snake or Forest Flame Snake (Oxyrhopus petolarius) in the rainforest close to La Fortuna.
This snake is rear-fanged and mildly venomous (not dangerous to humans). It eats mainly lizards and other snakes. Females are larger than males and can reach a length of 1 m (39 in). This species can be active in daytime and at night. It is a mimic of the highly venomous Many-banded Coralsnake (Micrurus multifasciatus).