With some of the highest peaks anywhere across the Caribbean Sea, the butterfly-shaped Island of Basse-Terre in Guadeloupe offers a fascinating alternative for the hours on end at the nearest beach. Towering amid the impressively high Soufrière massif on the island’s western half, La Citerne is an extinct volcano whose last eruption took place in 370 AD.

Instead of molten rock and clouds of ash, the now verdant volcano is topped by a well-hidden lake. Named by the French mountaineer Mr. Camille Thionville, Lac Flammarion is a measly 90 meters at its widest point, encompassing the bottom of the once magma-filled crater, 1,103 meters above sea level (3,619 ft).

But don’t let its miniscule size fool you as this secluded body of water apparently has some unique properties due to its geographical context. Since its watery content is replenished solely by rainwater, the lake’s waters feature an exceptionally high level of acidity, with a PH around 5. That in turn leaves the lake with nearly no living organisms within its confines.

Nevertheless, as it turns out, Lac Flammarion’s immediate surroundings are brimming with a couple of incredibly rare plants that happen to favor its acidic environment. Among the unique species of flora one can find here are Juncus guadeloupensis, Blechnum l’herminieri (a type of fern) and a plethora of endemic bulrushes. The lake along with the wooded volcano are part of the Guadeloupe National Park, and as such, are accessible by a series of hiking trails.

photography by: Stéphane Batigne/ Wikimedia Commons

photography by: Daniel Jolivet/ Flickr