Workers living in seaside areas in Great Britain earn on average £1,600 less per year than those living inland, BBC News analysis has found.
The research also found two-thirds of coastal areas had seen a real terms fall in wages since 2010.
The All Parliamentary Group for Coastal Communities said the findings showed seaside towns were "being left behind".
But the government said its £200m Coastal Communities Fund was changing lives.
This week BBC News is profiling what life is like in seaside communities across the country as part of the Coastal Britain project.
The most deprived places in England are found by the sea, according to government figures.
Struggling to pay rent
In Penzance in Cornwall young workers said they were struggling to find well paid, long-term employment by the coast.
"I love Penzance but I'm also sick of it," said 18-year-old Danny Hammond, who works as a waiter in a local restaurant.
"I earn £6.30 an hour, which isn't great and people older than me really struggle to pay the rent or the mortgage."
Tamia Mallam, 20, said many people she knew struggled in seasonal jobs connected with the tourism industry.
"When I worked In St Ives, between May and September there was lots of work because of the summer season, but then you'll be told suddenly that you're going to be unemployed. That is really tough," she said.
"There aren't many prospects for a career around here. It's a choice of working either in a boring retail job or as waitress."
Trainee carpenter Jack Slater was more optimistic about his future job prospects.
"Lots of my friends have moved away from Penzance to look for better paid jobs and that's why I want to get myself a trade," the 18-year-old said.
"I want to stay in Cornwall because it's beautiful and this is my home, and they're always building new homes round here which should mean I'll always have work."
The issue of low pay affects coastal communities across the whole country.
BBC News has analysed income data collected by the Office for National Statistics for 632 parliamentary in England, Scotland and Wales. Comparable data for Northern Ireland is not avaialble. Taking into account full and part time workers the analysis found:
- In coastal constituencies, the typical (median) worker in 2018 earned £22,104 before tax
- That was £1,681 less than the typical worker in a non-coastal area, who earned £23,785 before tax
- When inflation was taken into account annual wages fell in two-thirds of constituencies between 2010 and 2018, a "real terms" decrease
- The coastal constituencies of Wirral West and Weston-Super-Mare have seen real terms wages fall by around 25% since 2010
Low wages tended to be prevalent in coastal areas because a higher proportion of people worked in low skilled, low paid seasonal jobs.
A major report published by the House of Lords earlier this year said seaside towns had for too long been reliant on tourism to drive their local economies.
Mike Hill MP, chair of the all Parliamentary Group for Coastal Communities, said "for a long time coastal communities have felt forgotten".
"Many of these areas have lost industries like shipbuilding that once provided thousands of well paid jobs," he said.
"There's research that shows that without major changes, by 2030 places like my own constituency of Hartlepool could see lots of young people leave coastal areas, which underlines why we need the right investment to protect the long term future of our coastal towns."
At its party conference in September, Labour promised to build 37 offshore wind farms, which it claimed would generate more than 60,000 new well paid jobs in coastal areas.
The government said since 2012 its dedicated Coastal Communities Fund had invested more than £200m in seaside areas, while more than a quarter of the 100 towns initially selected to share its £3.6bn Stronger Towns Fund were on the coast.
Jake Berry, minister for the Northern Powerhouse and Local Growth, said these initiatives had begun to transform people's lives.
"For years government has only talked about creating growth in our cities. But we are investing in coastal areas and we've given councils across the country a real terms increase in their budgets for next year," he added.
This article is part of a special series from Penzance, Cornwall. BBC News is exploring the challenges and the opportunities for communities in Coastal Britain.