On the eerily inviting Hidden Valley Night Walk in Monteverde, Costa Rica, the creatures that one is likely to experience include tree frogs, snakes, spiders (including and especially tarantulas), agoutis, sloths, kinkajou, armadillo, plus an army of bugs and insects beyond your wildest dreams. 
Tarantula — Photo courtesy of jcantroot
Tours are offered at 5:30 pm and 7:30 pm and last for two hours; the earlier tour has the benefit of beginning with a beautiful sunset, during which the last of the songbirds can be seen and heard before they turn in for the night. As it gets darker and darker, the forest starts to wake up, and then the real fun begins. Another set of species emerges, and its members go on about their exotic routines that one could have previously only guessed at.
The tour is led by a bilingual guide well-versed in these nocturnal creatures and eager to explain the cacophony of unfamiliar sights and sounds made by the astonishing array of insects, reptiles, birds, and mammals that populate the forest of Monteverde at night. Housed on a privately-owned 11 hectare preserve, the Hidden Valley Night Tour is situated in what is considered pre-montane forest, which falls between a tropical wet and a seasonal moist forest, with an abundance of fruit-producing trees that make it an ideal habitat for a variety of birds, mammals and exotic insects not often seen elsewhere in Costa Rica, nor the world. Flashlights are provided, and long sleeves and pants are strongly suggested.
Adults: $25, Students: $23, Children under 10 years: $15