Hawaiian law prohibits the practice of 'shoreline armouring'. According to ProPublica, scientists claim that sea walls and other coastal defences such as sandbags are the leading cause of beach loss throughout the state. When waves hit the barriers, they pull sand from the shore and deposit it back into the ocean.

Despite this, a 2020 investigation revealed that almost 50 homeowners in Oahu alone had been granted permission to build new walls, keep illegally constructed walls and rebuild damaged ones over the preceding 20 years.

However, in a seeming crackdown on the practice, two homeowners at Sunset Beach were fined almost £789,000 ($1m) each in January 2024 for violations including the installation of sandbags and seawalls, and their failure to remove the structures.

20 towns being slowly swallowed by the sea