It's 8 a.m. and I'm nervous-sweating. "We cancelled our Cerro Chato tours today. It's very dangerous because of the rain," the tour operator says. "Very steep. Muddy. A lady broke her foot yesterday. And lot of snakes. You know, yellow ones."

I turn to look at Matt, seated next to me, contorting my face in an attempt to telepathically convey my answer. No way in hell. My heart is somersaulting. I'm trying to ignore the moisture steadily creeping through the back of my shirt. Snakes are a deal breaker for me.

"Thanks for your help," Matt tells the woman. "We're going to go talk to our friend to see what he wants to do."

An hour later, the three of us - Matt, Andrew and I - are ankle-deep in thick brown mud doing a kind of awkward Flamenco around tree trunks and lifted roots, arms raised and steps heavy. Our breaths resemble the labored gasps of a marathon runner. My glutes are searing. My pits are stained. And it seems like the steep uphill climb will go on for eternity.

Somehow, through the twisted knots of bark and jungle flora, none of us manage to lose our footing. At an 80 degree angle, we army crawl and scuttle crablike up the nearly vertical natural steps along the spine of the now-dormant volcano. The well-marked trail meandered through patches of pasture and dense forest before becoming veiled in misty sky.

An hour-and-a-half after the start of our ascent, the trail crested and the trees parted giving way to our own private view of Arenal, Cerro Chato's tall and imposing older brother. Below, we could just glimpse the glittering emerald waters of the 1,640-foot high lagoon, our consolation prize. All of a sudden, it was if the exhaustion and "I-should've-done-more-cardio-before-this-trip's" were worth it.

But our journey wasn't over yet.

The steepest part of our hike was actually the descent into Cerro Chato's hollow throat. Ravines dug from the dirt and clay were carved so deep they could swallow a human. Sunlight bled through curtains of fog. A few ropes and pulley systems were erected to ease in the ascent back to the top.

Balancing precariously on sturdy logs and grasping nervously at not-so-sturdy roots, we slowly eased ourselves down to the lagoon. A handful of wooden benches appeared, welcoming those choosing to forgo a dip, while a few protruding sticks served as clothing racks for those brave enough to swim. We, of course, chose the latter. [Note: Though swimming is allowed, the Observatory Lodge advises against it due to some of the minerals found in the water.]

Looking back, I can't remember what I was ever afraid of. We saw no snakes (thank God!). No one broke any bones. And, at the end of it all, we three agreed that this hike was the highlight of our entire Costa Rica trip.

How We Did It

• The route that begins near the Observatory Lodge and ends at the waterfall (which can also be done in the opposite direction) takes about 4-5 hours.  Another option involves leaving from the waterfall and returning along the same route. That generally takes about 2 hours of steep climbing to get to the top and another hour to get back down.
• There is an entrance fee of $8 per hiker if you wish to go without a guide.
• Budget at least 4 hours (or more, depending on your physical activity level) for the entire hike. For reference, we booked it up to the top in 1.5 hours, hung out at the summit, swam in the lagoon and completed a roughly 45-minute trek down.
• Bring water! There are no places along the route to replenish your water bottles/ Camelbaks.
• Wear appropriate clothing/ footwear. If I didn't mention it enough, this hike is STEEP. Grab a good pair of hiking boots, good socks and a rain jacket (just in case). Matt, Andrew and I all wore Merrells for the ascent/ descent, while Andrew brought a pair of Keens to wade around in the lagoon.