Things to Do in Costa Rica in October

October sits right in the middle of the Southern Hemisphere humpback migration, and Marino Ballena National Park, named for the whale-tail-shaped sandbar at Playa Uvita, is ground zero. Boats launch from Uvita and Bahía Drake in the early morning when the ocean is glassy and the Pacific still smells like salt and wet jungle. The whales breach, slap their tails, and occasionally swim close enough that you hear the explosive exhale of their blowholes before you see them. Mothers with calves are common, and the calves are curious enough to linger near boats. October's low visitor numbers mean smaller group sizes on tours, so you are not jostling twenty other cameras on a catamaran. Conditions are best before noon, when afternoon winds and chop pick up.

The Pacuare River in October is a different animal than the gentle Class II float of dry season. Rainfall swells it into a sustained Class III-IV run that drops through a canyon draped in primary rainforest, toucans overhead, howler monkeys screaming from the canopy, and the smell of wet earth and decomposing leaves thick enough to taste. The rapids hit in quick succession with names like Cimarrón and Huacas, and the water between them runs fast enough that you can feel the current pulling your raft even in the calm stretches. This is arguably the best whitewater in Central America during October, and the high water level makes the two-day trip with a jungle-lodge overnight worthwhile. The put-in is about two and a half hours east of San Jose, near Turrialba.

Tortuguero's black-sand beach, reachable only by boat or small plane, ranks among the most important green sea turtle nesting sites in the Western Hemisphere. October catches the tail end of the nesting season, and the beach at night is an otherworldly experience. No artificial lights allowed. You walk in near-total darkness behind a certified guide, the sound of surf mixing with the scrape of a 150-kilogram (330-pound) turtle hauling herself up the sand to dig her nest. The humidity is thick, mosquitoes are relentless, and the sand sticks to everything. Worth it. Watching a turtle lay eggs and then laboriously cover the nest with her flippers rearranges your priorities. The canals around Tortuguero village deserve a morning boat tour on their own. Caimans, river otters, kingfishers, and the occasional sloth draped over a branch like wet laundry.

While the Pacific side absorbs most of October's rainfall, the Caribbean coast around Puerto Viejo de Talamanca and Cahuita tends to catch a veranillo. This pocket of drier, sunnier weather feels like a cheat code. The vibe is radically different from the Pacific resort towns. Reggae and calypso drift from open-air bars. The food tilts toward Caribbean flavours. Rice and beans cooked in coconut milk, whole fried red snapper with ají picante, ripe plantains that caramelize on the grill until the edges go crispy and sweet. Cahuita National Park's coastal trail runs through jungle and along a reef where you can snorkel straight off the sand in waist-deep turquoise water, spotting parrotfish and brain coral with no boat ride required. Playa Cocles south of town has rideable surf for intermediates. Punta Uva's shallow cove is calm enough for small children. The air here smells different. Less volcanic loam, more salt and cacao, since working cacao farms line the road south of town.

Monteverde's cloud forest at night in October is something you hear and smell before you see anything. The air is cool. Noticeably cooler than the lowlands, hovering around 16°C (61°F) after dark. The air is saturated with moisture that beads on every surface, including your eyelashes. Your guide's red-filtered flashlight picks up eyeshine first. The reflective discs of a red-eyed tree frog clinging to a heliconia leaf. The unblinking stare of a kinkajou in the canopy. The delicate thread of a golden orb weaver's web strung across the trail and glittering with droplets. The smell is deep and vegetal, like a greenhouse turned up to eleven. October's wet conditions improve night walks because amphibians and insects are at peak activity. Daytime visits are excellent too. The night walk is the one that stays with you.

Manuel Antonio is Costa Rica's smallest national park and, per square metre, its most wildlife-dense. In October, with fewer visitors on the trails, the animals are bolder. White-faced capuchins drop to lower branches and stare at you with unnervingly human eyes. Three-toed sloths hang in cecropia trees along the main trail, close enough to count their claws. The park's beaches, Playa Manuel Antonio and Playa Espadilla Sur, sit inside the park boundary and are sheltered enough that the water stays swimmable most mornings even during green season. The trick is arriving when gates open. The early hours before the rain rolls in are when the forest is most alive. Howler monkeys calling territory from the canopy. Scarlet macaws crossing overhead in pairs so red they look painted. The damp forest floor releasing that unmistakable tropical smell of leaf litter and ripe fruit. By 1 PM, the rain usually pushes everyone out. That is fine. You will have seen more wildlife by then than most dry-season visitors see in a full day.