From grumpy volcanoes to labyrinthine limestone caves to stunning black-sand beaches, Costa Rica offers a never-ending array of natural wonders that keep visitors coming back.

Here are 10 natural wonders that make this Central American gem one of the most popular destinations in the world.

From 1968 until 2010, Volcán Arenal was an ever-active and awe-striking natural wonder, producing menacing ash columns, massive explosions and streams of glowing molten rock almost daily.

While the fiery night views are gone for now, this mighty mountain is still a worthy destination. The park is rugged and varied, with about 15km (9.3 mi) of marked trails that follow old lava flows.

Hikers routinely spot sloths, coatis, howler monkeys, white-faced capuchins and even anteaters.

Canoeing the canals of this park is a boat-borne safari: here, thick jungle meets the water and you can get up close with shy caimans, river turtles, crowned night herons, monkeys and sloths.

In the right season, under cover of darkness, watch the awesome, millennia-old ritual of turtles building nests and laying their eggs on the black-sand beaches.

Sandwiched between extravagantly green wetlands and the wild Caribbean Sea, this is among the premier places in Costa Rica to watch wildlife.

Here is a virginal forest dripping with mist, dangling with mossy vines, sprouting with ferns and bromeliads, gushing with creeks, and nurturing rivulets of evolution.

Reserva Biológica Bosque Nuboso Monteverde came into being in 1972. The Quaker community had already set aside a third of its property for preservation...

But spurred on by the threat of encroaching squatters, it joined forces with environmental and wildlife organizations to purchase and protect an extra 328 hectares (811 acres) of land.

Today the reserve totals 41.25 sq km (26,400 acres). Because of the fragile environment, the reserve allows a maximum of 250 people at any given time.

So as not to miss out, get there before the gates open, or better yet, come during the off-seasons. A night tour or overnight stay will maximize your chances of spotting wildlife.