Panama’s many reptile species contain several that make visitors most nervous about the tropics: venomous snakes. It’s unlikely you’ll encounter any snakes at all during a hike, and highly unlikely any will bother you if you don’t bother them.

That said, one of the country’s most venomous snakes is also one of the most prolific: the fer-de-lance (Bothrops asper), a pit viper more commonly known in Panama as an equis (“X,” for the diamond or X-pattern on its brown skin) or a terciopelo (which means “velvet”).

A full-grown adult can be more than 2 meters long. The females give birth to up to 50 young at a time, which are born venomous and can actually be more deadly than an adult because they have not learned to regulate their venom. Fer-de-lance can be aggressive, especially during mating season.

Another forbidding creature is the bushmaster (Lachesis acrochorda, Lachesis muta, and Lachesis stenophrys), the world’s largest viper and the largest venomous snake in the western hemisphere. Known locally as a verrugosa (“the warty one”), it can grow up to three meters long, but is much more rarely encountered. That’s a good thing, since its bite has a high fatality rate.

The eyelash palm pit viper (Bothriechis schlegelli) comes in an assortment of brilliant colors. It’s quite beautiful and sinister-looking at the same time (a snake fancier in Panama once described its visage as “unmasked malice in pure form”).

Panama also has several species of coral snake. Assume any coral snake you encounter is dangerous—the rhymes used to distinguish venomous from nonvenomous corals in the United States do not work in Panama.

Other notable venomous snakes include jumping pit vipers (Atropoides nummifer and Atropoides picadori), known locally as mano de piedra (“hand of stone”) and patoca. The yellow-bellied sea snake (Pelamus platorus) is commonly known as the Pacific sea snake since they only occur in the Pacific and Indian Oceans (the risk of it spreading to the Atlantic was an argument against building a sea-level canal). Its venom is deadly, but it is not aggressive and is rarely encountered—in all my years in Panama, I’ve come across just one, and it had washed up on the beach, dead.

Nonvenomous but potentially dangerous snakes include the boa constrictor, which averages a little under two meters long and can bite if provoked. There are also plenty of harmless snakes, including a variety of vine snakes.

Caimans (Caiman crocodilus) are, despite their scientific name, a kind of alligator found in great abundance in some of Panama’s rivers. They’re easy to spot in Gamboa. They are generally small and rather placid, though some can grow to be about 2.5 meters long. There have been reports of the far larger American crocodile (Crocodylus acutus) in the waters of the Panama Canal, especially around Gamboa, though this endangered species can be hard to find. It spends most of its time in estuaries on the Pacific side of the isthmus. On a recent trip to the Darién, I encountered an enormous one on a sandbank on the Río Tuira.

Green iguanas are a protected species in Panama, but they are sometimes still hunted as food. Efforts are being made to reintroduce iguanas in various parts of the country.