Costa Rica’s Iconic & Impressive Arenal Volcano

Arenal Volcano, a cone-shaped stratovolcano, is, quite frankly, the rock star of La Fortuna these days, attracting visitors from all over the world now that it’s at rest. After spending a few days in its shadow, I can’t imagine never having been in its presence. It’s that awesome.

During our group’s stay at Arenal Paraiso Resort and (thanks to the volcano) enjoying the warmth of its thermal mineral hot springs, we had the opportunity to learn from a knowledgeable national park ranger all about this amazing behemoth.

There are close to 300 volcanos in Costa Rica, but Arenal is one of only five that are considered active. It’s also the youngest, at 7,000 years old. To put that in perspective, one of the country’s volcanos is a million years old!

The last time Arenal Volcano came alive was in 1968. Before that, it hadn’t erupted since the year 1525. But in the eruption of ’68, lava chunks the size of school buses rained down. Pyroclastic flows burned everything in their path, with lava traveling at 80 mph at temperatures over 200 degrees Fahrenheit. For a little over 40 years after that, through 2010, the volcano continued from time to time to spew hot gases, ash and giant boulders, making it one of the most active volcanoes ever. Now, it’s quiet, and is not expected to erupt again for at least another hundred years.

If you’re heading to Costa Rica to see this mighty volcano, don’t worry. Scientists have a lot more knowledge than they did back when it last started to erupt, which would allow for plenty of notice should Mother Earth start giving off signals that the volcano is waking up again (signs like tremors and venting).

Experts who have studied the years that led up to Arenal’s 1968 eruption realize now that one of the biggest clues the mountain was about to roar back to life went unrecognized — which was that fumaroles had begun forming. Fumaroles are openings at the surface of a mountain, from which volcanic gases and hot vapors vent. They’re one of the most important signs a volcano is becoming active.

Those fumaroles, in fact, remain active to this day. That’s why you can still see steam on the volcano after it rains, and it’s also why there is still hot runoff leading to so many thermal springs in the area. And by hot I mean at least 100F! Those natural mineral springs sure do attract a lot of visitors who want a relaxing soak while gazing up at the volcano that provides those naturally heated waters.

Arenal Volcano is part of the Ring of Fire, which is a horseshoe formation of volcanoes surrounding the Pacific in 31 countries, where 92% of the world’s earthquakes occur. The shifting of tectonic plates some 200-million years ago is actually what brought Costa Rica up to the surface from under the sea, where it emerged as a land mass. And those tectonic plates continue to shift. In June of 2023, Costa Rica felt the highest number of tremors yet — 864!

Two positive things that have come about since Arenal’s destructive behavior are the formation of a national park and a manmade lake  —  Arenal National Park and Arenal Lake.

Arenal National Park was created in 1992, two kilometers surrounding the base of the volcano that provide protection for the regrown rainforest. Howler monkeys, sloths and dozens of species of colorful birds call that forest their home. The rich volcanic soil also nourishes thriving flora. With 3.2 million people traveling to Costa Rica each year, many whom specifically come to explore the volcano and wildlife, local guides are taking advantage of the opportunity to educate visitors (in between adventures such as zip lining and hanging bridge hikes) on the importance of protecting Costa Rica’s rainforests in the hopes of influencing their behavior toward conservation.

Oh, and if you’re among the adventurers intent on making it 5,437 feet up to Arenal’s summit, it would take you about five hours to reach the peak. Just make sure you get back down the mountain by 4 p.m., when the park closes for the day.

Arenal Lake and dam were made to produce hydroelectricity. Its beautiful waters also provide recreational opportunities, especially boating. Sailing across the width of the lake is a great shortcut to reach the base of the Monteverde mountain range (rather than spending the several hours it would to drive there from the volcano). Crossing Arenal Lake will take your breath away as you visibly embrace the mountains, wildlife, and, of course, the imposing Arenal Volcano that surround you.

To experience Arenal Volcano, its hanging bridge rainforest parks and Arenal Lake, A Taste of Costa Rica might be just the program for you. But there are also many more experiences in this biodiverse hot spot of a country that Road Scholar has to offer. So be sure and check out our entire collection of learning adventures in Costa Rica to find the one that’s right for you!