Diving In Lago De Atitlan (ati Divers, La Iguana Perdida, Guatemala)

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Diving in Lago de Atitlàn

ake Atitlàn is a freshwater lake formed in a volcanic caldera at an altitude of 1560 m (5160 ft). The lake is roughly 320m deep—one of the deepest in the world—though because of altitude diving considerations and reduced visibility at depth, few divers go deeper than 25m. Visibility averages 10 m in the dry season but varies widely from 3 to 14 m depending on recent rainfall, depth, and bottom composition. Temperature varies year-round from 23˚C in the wet to 20˚C in the dry season. Atitlàn offers rare diving opportunities in a geothermically active, high-altitude, temperate environment. There are few places in the world where you can dive at altitude while wearing a wetsuit, since most high-altitude lakes are glacier-fed. If that’s not enough, you can plunge your hands into volcanic hot spots, search for ancient Mayan pottery, swim next to gigantic rock formations and through volcanic swimthroughs, or join the fish among the branches of the lake’s still-standing petrifying trees. Our dive sites vary in bottom composition— from stunning, sheer walls to sloping, silty bottoms—and offer an assortment of plant life, freshwater crabs and various lake fish, including black bass, perch, crappie and cichlids. The crowning feature of all dives here is the stunning panoramic view, upon surfacing, of what Aldous Huxley called the most beautiful lake in the world. From beginners to experienced instructors, guests of Ati Divers are stunned at the beauty of the sheer walls and incredible rock formations that line the lake. The geothermal hot spots make an exciting end to a dive that give you

a hands-on experience with volcanism that can be repeated in few other places on the planet. If you’re on your way back from the Caribbean, Lake Atitlàn makes an interesting contrast to your tropical dives. It is a unique experience that combines altitude, geothermal activity, fresh water, and some stunning volcanic walls: overall, a place like no other you will ever visit.

“plunge your hands into volcanic hot spots, search for Mayan pottery, take in gigantic rock formations and volcanic swim-throughs, or join the fish among the branches of the lake’s petrifying trees.”

You may be surprised at how much of a difference the altitude makes to your buoyancy control. The reduced air pressure at the surface—roughly 0.85 atmospheres of pressure compared with 1 atmosphere at sea level—means there is a greater change in pressure per metre of water you ascend or descend. This means that buoyancy adjustments are needed more frequently and it is harder to manage small changes in depth

using the lungs alone: be prepared to feel like a beginner again for the first few minutes of the dive. Ultimately, though, the experience will improve your buoyancy control. One important note: driving to altitude considerations require divers to spend the night on the lake after diving here. Heading to Antigua, Chichi, Guatemala City, etc. requires a climb up out of the lake basin and can lead to decompression sickness if done too soon after a dive. You must wait until the day after your last dive before leaving the lake.

“If you are used to diving in warm, crystal waters filled with tropical fish and coral reefs, Lake Atitlàn is a unique, exotic location.” About Ati Divers Ati Divers is one of only two dive centres operating on the lake, and the only one in Guatemala that caters to tourists. We offer a full range of PADI courses, from Open Water to Divemaster and, uniquely, the Altitude Specialty Diver course.

Ati Divers and La Iguana Perdida, the hotel that houses the dive centre, were established 10 years ago by Davina (Deedle) Ratcliffe and her then-partner. The couple had originally come to participate in an underwater lake mapping project. When the project fell through, they opened a dive centre instead. Deedle now runs the Iguana and Ati Divers with her American husband Dave Ratcliffe (who, incidentally, started out as a hotel guest seven years ago). Deedle is a PADI instructor and Dave is a divemaster. Local History and Archaeology Occasional pieces of ancient Mayan pottery have been found by divers on the lake, particularly by Guatemalan Roberto Samayoa. Many of the artifacts that he’s recovered over the years have been restored and dated and are now displayed in the Museo de Lacustre, housed in the Don Rodrigo hotel in Panajachel. The museum also has a room dedicated to the lake’s natural history, explaining how the lake was formed over the millennia. Guests of Ati Divers get a discounted admission fee.

The Origins of Lago de Atitlàn

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ost active volcanoes in Mexico and Central America occur in a belt produced as the crust of the Pacific Ocean is forced under the North American and Caribbean tectonic plates. As a result, Guatemala lies in the middle of one of the world’s many volcanic hotspots. The explosive eruption of Guatemala’s Santa Maria volcano in 1902 was one of the largest eruptions of the twentieth century. Three large calderas have formed in the Atitlàn region in the past 14 million years. The modern Atitlàn (III) Caldera’s story began 150 000 years ago, when a magmatic batholith—a huge subterranean pocket filled with liquid magma—formed in the area that is now the lake. By 100 000 years ago, there were at least three volcanoes in the area being fed by the Los Chocoyos Batholith, though these volcanoes are today partially or completely destroyed. After thousands of years of building up pressure, the Los Chocoyos Batholith finally discharged 84 000 years ago in a massive, violent expulsion of over 250 cubic km

Major volacanoes of Guatemala.

of magma, ash and sand. The eruptive column reached heights of 40–60 km. After its collapse, the batholith continued to spew magma and scolding ash, scorching everything it came Lago de Atitlàn as seen by into contact with as satellite. it advanced over a massive area. Finally, so much magma had been expelled that only an empty cavity was left where the magma had been. Unable to support “After thousands of years of building up pressure, the Los Chocoyos Batholith finally discharged 84 000 years ago in a massive, eruption that reached heights of 40-60 km.” the weight of the earth above it, the entire area collapsed, forming the 18km-diameter cauldron (known to geologists as a caldera) that became the lake, and collapsing the existing volcanoes with it. While to most people the lake is only 300-or-so metres deep, its geological depth is actually closer to 900 m. The caldera is lined with sediment for 300 m before being partially filled by another 300 m of water. The last 300 m of the caldera are filled with air: you can see the geological top of the caldera when you look east across the lake at the tops of the cliffs above Panajachel.

Atitlàn today Since the major caldera-forming eruption 84 000 years ago, three new volcanoes have formed in and around the southern boundary of the lake: Vulcan San Pedro (60 000 years ago), Vulcan Toliman and Vulcan Atitlàn (both 30 000–40 000 years ago). Atitlàn is the youngest and most active of these volcanoes and its activity continues to give the lake its present day shape. According to diving records, ancient ruins from Mayan and preMayan cultures occur in Santiago Bay. This and other evidence suggests that Vulcan Atitlàn produced lava flows that dammed the lake outlet (formerly located just south of the town of San Lucas Toliman) within the last 3000 years. A 30 metre-high saddle now prevents surface outflow from the lake. The first recorded eruption of Atitlàn was in 1469. Vulcan Atitlàn last erupted from 1826 to 1856. The eruption in 1853 was short but quite strong and caused complete darkness around the lake for four hours. Aside from the eruptions of Vulcan Atitlàn, little is known about the unrest at Atitlàn Caldera. Seismic activity has been low during the past decade or more. Volcanic activity does influence relatively long-period fluctuations in the lake’s level. The lake level was reportedly low in the 1820s, 10–15 metres higher in the 1870s, low again in the 1920s, and high again from the 1940s to the present. Most of the lake level’s fluctuation is due to variation in annual rainfall (increasing the lake level) or the effects of regional earthquakes on the the lake’s

underground drainage system (generally decreasing the lake level). Short-term changes in lake level attributable to rainfall may be as great as 3.3 m, an increase seen during the exceptionally wet year of 1933. Changes attributable to earthquakes may be as great as 2 m, a drop recorded a month after the Guatemala earthquake (magnitude 7.5) of February 1976. It is unknown whether there is any uplift and shifting of the caldera floor affecting the lake level. Hurricane Stan Early in the morning of October 5, 2005 a lahar (a torrential flow of water and rock fragments down the slopes of a volcano and looking like a mass of wet concrete carrying rock debris up to the size of boulders more than 10m in diameter) generated by heavy rainfall from Hurricane Stan destroyed the town of Panabaj and buried hundreds of people. As of October 10 at least 200 people had died and hundreds more were missing. Heavy continuous rains between October 4 and October 8 caused numerous mudslides and debris flows throughout the Guatemalan highlands. In the Atitlàn region, Santiago suffered major losses. The towns on the north side of the lake—including Santa Cruz—were also hit, though not as badly as those on the south side, nearer the volcanoes. Flooding knocked out key highway bridges and hampered rescue efforts.