What is a lake? Well, there's no good, agreed on definition. Most will agree that a lake is a body of water completely surrounded by land, but there are many other characteristics that hydrologists debate. How big should a lake be? Where is the line between a lake and a pond? A pond and a pool? And between a pool and a puddle? How deep should it be? When does a pond overgrown by a vegetation become a marsh?

Hydrologists agree that some of the boundaries are arbitrary. For example - different definitions of a minimum size for a lake range between one hectare and as much as 40 hectares in surface area. For our purposes - high altitude lakes - we need to choose and set the boundaries ourselves:

  • A lake must be at least 100x100 meters in size*. If it is not perfectly round, a sum of dimensions equal to or greater than 200 meters will also be accepted (e.g. 140x70m, 150x60m, etc.). Width must be 30 meters or more.
  • A pool must be at least 30x30 meters in size. As above, a sum of dimensions greater than 60 meters is ok, too. Width must be 10 meters or more.
  • A lake or a pool must be deeper than 2 meters.
  • A lake or pool must be perennial (it can not be a seasonal lake). It should meet the above criteria year round.
  • If it is frozen (partially or completely), it must thaw once per 5 years, at least for the summer.
  • *Indian Space Research Organisation uses a nominal 1 hectare area (essentially 100x100 meters) for the smallest lakes in their National Wetland Inventory and Assessment for High Altitude Himalayan Lakes.


    In order to put a lake/pool on a list we need good evidence that it really exists. Why do we bring up this topic? Well, the reason is that some high altitude lakes have been put on maps (even state-of-the-art maps) and they are not really there. We have experienced this ourselves in March 2012, when looking for Laguna del Muerto - a pool in the Ojos del Salado area at elevation of 5020m. We were using a map that was considered "THE map" by tour operators and guides working in the area. Still, after an hour or so combing the area with our noses glued to two Garmin handsets, we concluded that there was no pool there. Later on we have studied satellite photos and it seems that the lake simply dried out.

    What constitutes good evidence? There is a saying: "Pics or it didn't happen". So, the best evidence will be a visual confirmation of the lake/pool existence. Pictures and videos taken when visiting an area are conclusive. Good quality aerial photos are also considered very good evidence. Next, we will also accept satellite photos, if they are of reasonably good quality. However, if resolution or quality is poor, it is possible to mistake another object - a glacier, a flat firn field or even a shadow of a cloud - for a lake. Google Earth is a good source of photos with reasonable quality. We will also accept climber's first-hand written reports, but we will always look for a visual confirmation.

    Near-lakes and Ex-lakes


    Bodies of water at high altitude are in continuums - of area, length, width and depth. Some of them may change their size dramatically during a year - they may be fed with molten snow in the wet season and then lose a large portion of their volume through evaporation in the summer. They may also freeze, and may not thaw for more than one year. When a lake is frozen for several years, is it still a lake that sometimes freezes, or rather a glacier that sometimes thaws? There are no good answers, and this is why we have set the above rules for a body of water to be qualified as a lake (or pool). However, there will be some bodies of water that 'almost' make it to be qualified - we'll call them near-lakes. They may be important for some reason, let's not lose sight of them. Examples of near-lakes:
  • A body of water that meets the size criteria, but is shallower than 2 meters.
  • A body of water that is located in an unstable terrain and substantially changes its shape from year to year
  • A body of water that is frozen and did not thaw for more than 5 years.
  • A body of water that is known/important, but does not meet size limits (e.g. Damavand pool)
  • A body of water that meets the size limits during wet season, but doesn't meet them during the dry season.

  • Ex-lakes

    As mentioned above, lakes sometimes disappear. They dry out due to changed precipitation/evaporation ratio or are receiving less water from melting snow and ice. They may drain due to changes in surrounding terrain. If we cannot confirm a lake's existence (and it was previously reported by climbers or put on a topo map), it is not strong enough reason to conclude that it does not exist. Only when we have an evidence of non-existence, such as a dry basin in a place where we'd expect a lake, we will conclude that the lake has died. We will maintain a list of them. Who knows, maybe with a change of climate a lake may re-appear.