A new sign at the popular Mermaid Pools at Matapouri Bay warns swimmers that although the rockpools are beautiful, they can also be perilous.
Department of Conservation (DoC) staff put up the sign on the headland above the pools last week ahead of the expected summer influx of visitors.
A spokeswoman said swimmers often thought they were safe from the big coastal swell.
Some locals had called for warning signs as the pools became more widely known.
Following a 2010 rockfall that blocked the former low-tide-only access to the pools, a track was built over a steep headland and now gives access during any tide.