STATUS: Lake Alexander is currently open for swimming. This status is kept up to date as part of regular water quality monitoring and any other reasons for closure. Last updated: 17 April 2025.

Situated in East Point Reserve, Lake Alexander is a picturesque body of water that is suitable for recreational activities throughout the year.

The site of Lake Alexander was originally an area of low-lying coastal marsh but was developed into a man-made lake for recreational use in 1991. The lake covers 3.5 hectares and has a maximum depth of 2.8 metres.

Fresh seawater is pumped into Lake Alexander each day during high tide. A filter on the pump limits the risk of box jellyfish and Irukandji from entering the lake.  

Recreational Activities

Lake Alexander is a popular location for recreational activities both in the water and on the shore. It's great for paddle boarding, swimming and a variety of non-motorised watercraft, or finding a shady spot for yoga or a picnic. Please note that the use of motorised watercraft and fishing in the lake is not permitted. 

Water Quality Monitoring

City of Darwin undertakes regular water quality monitoring at Lake Alexander.

Water quality is sampled for bacteriological contamination (Enterococci). This is carried out in accordance with the requirements set out in the National Health and Medical Research Council Guidelines for managing risks in recreational water and the City of Darwin Water Quality Sampling Procedure.

Users are advised to take care on site, obey all signs and swim at their own risk. There are no lifeguards present on site. 

Cassiopea jellyfish

Cassiopea spp. or 'upside-down' jellyfish are known to bloom seasonally in Lake Alexander, particularly when the salinity increases towards the end of the dry season. These unusual jellyfish rest upside-down on the lakebed with their feeding arms outstretched.

Cassiopea spp. polyps persist in the lake year-round but only grow to their adult form when conditions are favourable.

Contact with these jellyfish may cause stings or skin irritation in some people, particularly children. If you see these jellyfish, please consider staying out of the water until blooms naturally subside, or otherwise take care to avoid contact if entering the water. If irritation occurs, apply an ice pack to reduce swelling. Do not apply freshwater or vinegar or rub the area, as this will cause more stinging cells to be released. 

More information

For more information or to access the latest water quality results, please contact environment@darwin.nt.gov.au.