The Cook Islands environmental group, Te Ipukarea Society, is triallling a different approach to sea-wall construction.
With funding support from the Australian Government through the Global Environment Facility to combat climate change, the organisation is experimenting with heavy duty, geotextile sandbags as a sea barrier at Avana Harbour on Rarotonga.
Te Ipukarea's Kelvin Passfield said a rehabilitation of the zone around the Avana jetty five years ago, using large granite boulders, led to further erosion.
He said Rarotonga's reliance on boulders to keep the sea at bay could make the problem worse.
"They have their own impacts from scouring in front of the boulder walls and erosion at the ends - they call that end effect, from when you put up a solid wall like that.
"You can expect you'll get similar thins with the sandbags I think but not as severe. As I said this is a pilot project. It's never been tried before," he said.
Passfield said while the sandbags may also be washed away in a cyclone, as they inevitably will be, they would not cause the level of destruction the boulders did, and the remnants of the sacks could easily be cleared away.
And he said ending boulder use would have another advantage - stopping quarrying in the centre of the island.
Passfield said the GEF funding also allowed Te Ipukarea to set up schemes in Niue and Tokelau.
He said the Tokelau project involved providing drinking water stations on the three atolls and in Niue they were brought in to help with organic farming and composting.