Water Safety New Zealand expects beaches to be inundated this summer and is calling on everyone to take extra precautions to stay safe.
It says New Zealanders trapped at home because of the global pandemic are likely to explore local holiday spots.
The organisation's spokesperson Ben Christie said swimming between the flags is usually the best place to swim, even if it is crowded.
"There needs to be an element of personal responsibility this summer, I mean the safest place for anyone to swim is between the flags at a patrolled beach and if in doubt, stay out."
He said empty beaches are sometimes empty because of dangerous swimming conditions.
"It's about getting that local knowledge as well when you're travelling around on holiday this summer going to different places, when you might not necessarily be familiar with the conditions, it's really important that people read signage and get that local knowledge [so] they know what the risks are."
Christie said swimmers should watch for rips, be wary of unpatrolled coastlines and check the forecast.
He said swimmers should know their limits, be aware of the dangers, and keep track of the other people they are swimming with.