Gwynedd, Neath Port Talbot and Bridgend are among the areas of worst deprivation in the UK, according to a new study.
The report compared earnings, employment, health and education data in local authority areas and identified 'pockets of deprivation' in seaside towns and coastal communities.
Analysis by the Social Market Foundation (SMF) think tank found that 85% of Great Britain's 98 coastal local authorities had pay levels below the national average for 2016.
The research commissioned by BBC Breakfast found that Gwynedd was one of the 10 local authorities in Great Britain with the lowest average employee pay.
Neath Port Talbot and Bridgend made up some of the 20 local authorities in England and Wales with the highest proportion of individuals in poor health.
The author of the report and Chief Executive of SMF, Scott Corfe, says the areas lack of infrastructure is leading to the deprivation level.
Many coastal communities are poorly connected to major employment centres in the UK, which compounds the difficulties faced by residents in these areas. Not only do they lack local job opportunities, but travelling elsewhere for work is also relatively difficult.
The UK Government has pledged to give £40 million to coastal areas in a bid to boost employment and encourage tourism.
This Government recognises the challenges facing coastal communities and our investment in local growth is already making a big difference. We've also announced today another £40 million of Government funding to further boost economic growth and create jobs.