How does it work?

Know which lakes to swim

There are a few places in the South Island which are very sacred to Māori and can't be swum in. Similarly, certain lakes are protected for environmental reasons.

Please do not swim in lakes that are sacred and/or protected.

All of these lakes should not be on the Lake Attack map. If there are lakes on our map that you know are forbidden, please let us know and we will remove them.

Lakes we know are not to be swum:
  • Rotomairewhenua / Blue Lake
  • Rotopōhueroa / Lake Constance in Nelson Lakes National Park.


Before you start a swim, please make sure you have read the text below. We would love to see every lake on the South Island swum, but we care about your safety a lot more! Some of the lakes on the list might not be feasible for a variety of reasons, such as:
  • They might be impossible to reach because they are too far away - some in the Fiordlands might be a bit too much...!
  • The water quality is not suitable for swimming (see the next chapter for more details)
  • The lake is on private land, and cannot be accessed without permission
  • Swimming in the lake is risky due to currents, other lake users (such as boats) or environmental hazards
As with all outdoor activities, please make sure that you undertake these activities safely! We cannot take responsibility for all your adventures, but do want to encourage everyone to have a fun time and prioritise coming back safely over having the swim.

Don't swim alone, and if you have a floatation device - bring it. And as the expression goes: when in doubt, stay out!

Enjoy your swimming but don’t spread invasive species

There are several highly invasive species present in the South Island that would just love to hitch a ride with you to another waterway. Yes definitely didymo. But also lake snow (lindavia) – an algae that causes patches of sticky, slimy mucus in lakes. And lagarosiphon – a monster of a weed that engulfs and shades out the native species and breaks into clumps that rot on the shore.

The most high-risk gear is made of absorbent material – wetsuits, togs, towels, even hair. A wetsuit can stay wet enough to support life for 6 to 7 days if it’s not dried correctly.

To keep our beautiful lakes safe, there are 3 simple but essential steps to take after every swim:
  • Check – remove anything weedy you can see – throw it on the lake edge or in a bin.
  • Clean – soak your gear in a 10% mix of dishwashing liquid and water and leave it to soak for 10 minutes before rinsing. (This is because you won’t necessarily see an algal cell, weed fragment or egg on your gear, so it’s critical you clean it thoroughly.)
  • Dry – if you can, dry your gear completely to touch, inside and out, and then leave it for at least another 48 hours before you use it again. (Invasive weeds and pests need dampness to survive so don’t give them that chance.)
Another good option is to use a different set of gear for each swim. And make sure you Check, Clean and Dry your hair.

Make these steps part of your Lake Attack routine. It takes all of us to protect our lakes from the spread of invasive weeds and pests.

How to submit a swim

  • Choose a lake in the South Island. Make sure it is also available on the website - we are only counting the named lakes according to Topo250
  • Make your way there and swim in it (safely) for 10 minutes or more
  • Log in to this website. If you need the password, just check our Facebook page.
  • Enter all the swim details and hit submit. Optional: upload a cool picture to the Facebook page and share your swim.
  • Choose another lake and repeat!
If there are lakes missing, or you made a mistake - just send us a message on, and we'll try to get it sorted!

Feel free to the website with any keen swimming or sporty friends and whānau or other groups and clubs.

A swimmer near Kelvin Heights - Queenstown

Interactive Swim Map

Click on a lake for more information.
Or (in case of a touch-screen) hold down on the lake for a few seconds.

Click on a lake for more information!

Swimming Statistics

Number of lakes completed: 94 / 356 (26%)

26% Complete

Total number of swims: 271

Most recent swim
Lee Dalton in Little Sylvester Lake on 2023-04-30.
Lee Dalton in Lake Sylvester on 2023-04-29.
Sandra Mcgregor in Lake Rotoroa on 2023-04-17.

Most swims
Joanne Brewin with 35 swims.
Glen Harry with 31 swims.
Jacob Marriott with 25 swims.

Longest time
Sue Beale with 620 minutes.
Joanne Brewin with 466 minutes.
Jacob Marriott with 400 minutes.

Furthest swimmer
Sue Beale with 23658 metres.
Renee Wedd with 21800 metres.
Glen Harry with 15013 metres.

Swimming in Lake Wakatipu, near Glenorchy