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Lake Atitln is a freshwater lake

formed in a volcanic caldera at an

altitude of 1560 m (5160 ft). The lake

is roughly 320m deepone of the deepest

in the worldthough because of altitude

diving considerations and reduced visibilityat 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 23C in the wet to 20C in the dry

season.

Atitln offers rare diving opportunities

in a geothermically active, high-altitude,

temperate environment. There are fewplaces in the world where you can dive at

altitude while wearing a wetsuit, since most

high-altitude lakes are glacier-fed. If thats

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 swim-

throughs, or join the sh among the branches

of the lakes still-standing petrifying trees.

Our dive sites vary in bottom composition

from stunning, sheer walls to sloping, silty

bottomsand offer an assortment of plant

life, freshwater crabs and various lake sh,

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 experiencedinstructors, 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

Diving in Lago de Atitln

a hands-on experience with volcanism thatcan be repeated in few other places on the

planet. If youre on your way back from the

Caribbean, Lake Atitln 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.

You may be surprised at how much of

a difference the altitude makes to your

buoyancy control. The reduced air pressure

at the surfaceroughly 0.85 atmospheres

of pressure compared with 1 atmosphere at

sea levelmeans 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

plunge your hands intovolcanic hot spots, search for

Mayan pottery, take in giganticrock formations and volcanic

swim-throughs, or join thefish among the branches of the

lakes petrifying trees.

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using the lungs alone: be prepared to feel like

a beginner again for the rst 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.

About Ati DiversAti 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 andher 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 ArchaeologyOccasional pieces of ancient Mayan

pottery have been found by divers on the

lake, particularly by Guatemalan Roberto

Samayoa. Many of the artifacts that hes

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 lakes natural

history, explaining

how the lake was

formed over the

millennia. Guests

of Ati Divers get

a discounted

admission fee.

If you are used to diving inwarm, crystal waters filled

with tropical fish and coral

reefs, Lake Atitln is aunique, exotic location.

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Most active volcanoes in Mexico

and Central America occur in a

belt produced as the crust of the

Pacic Ocean is forced under the North

American and Caribbean tectonic plates. As

a result, Guatemala lies in the middle of oneof the worlds many volcanic hotspots. The

explosive eruption of Guatemalas Santa

Maria volcano in 1902 was one of the largest

eruptions of the twentieth century.

Three large calderas have formed in the

Atitln region in the past 14 million years.

The modern Atitln (III) Calderas story

began 150 000 years ago, when a magmatic

batholitha huge subterranean pocket lled

with liquid magmaformed in the area thatis 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 nally

discharged 84 000 years ago in a massive,

violent expulsion of over 250 cubic km

The Origins of Lago de Atitlnof magma, ash

and sand. The

eruptive column

reached heights of

4060 km. After

its collapse, thebatholith continued

to spew magma

and scolding

ash, scorching

everything it came

into contact with as

it advanced over a

massive area.

Finally, so much magma had been expelled

that only an empty cavity was left wherethe magma had been. Unable to support

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 lled by another 300m of water. The last 300

m of the caldera are

lled 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.

After thousands of years ofbuilding up pressure, the LosChocoyos Batholith finally

discharged 84 000 years agoin a massive, eruption that

reached heights of 40-60 km.

Lago de Atitln as seen by

satellite.

Major volacanoes of Guatemala.

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Atitln todaySince the major caldera-forming erup-

tion 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 Atitln (both

30 00040 000 years ago).

Atitln 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 pre-

Mayan cultures occur in Santiago Bay.

This and other evidence suggests that

Vulcan Atitln produced lava ows 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 outow from

the lake.

The rst recorded eruption of Atitln was in

1469. Vulcan Atitln 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 Atitln,little is known about the unrest at Atitln

Caldera. Seismic activity has been low during

the past decade or more.

Volcanic activity does inuence relatively

long-period uctuations in the

lakes level. The lake level was

reportedly low in the 1820s, 1015

metres higher in the 1870s, low

again in the 1920s, and high again

from the 1940s to the present.

Most of the lake

levels uctuation

is due to variation

in annual rainfall

(increasing the lake

level) or the effects of

regional earthquakes

on the the lakes

underground drainage system (generally

decreasing the lake level). Short-term

changes in lake level attributable to rainfallmay 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 oor affecting the lake level.

Hurricane Stan

Early in the morning of October 5, 2005 alahar (a torrential ow 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 ows throughout the Guatemalan

highlands. In the Atitln region, Santiago

suffered major losses. The towns on the

north side of the lakeincluding Santa

Cruzwere 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.