These benefits are threatened by marine pollution, coastal development, climate change and exposure to extreme weather.
Visiting beaches, rocky shores and coastlines boosts people's happiness and wellbeing, research shows.
Coasts have a therapeutic effect on people, boosting wellbeing and mental health, the evidence statement drawing on 46 peer-reviewed papers and published by the Environment Department (Defra) said.
People also report feeling more restored when they spend time in areas around the coasts, compared to urban parks and green spaces, and find the seascape as beneficial as woods and mountains.
And people are happiest when spending time by the sea, compared to other natural environments, the study said.
The review also highlights the importance of protecting marine areas, as people feel more restored and happier when there are more signs of wildlife, natural conditions and less litter on the beaches and shores.
It warns the environment around the coasts is affected by water and air pollution and the impacts of climate change such as rising seas, flooding and extreme weather, as well as inappropriate development.
In England, 271 million recreational visits are made to coastal environments a year, and over a third of the UK population live within 5km of the coast, Defra said.
People use more energy while they are visiting the seaside, because they spend longer there than on trips to the countryside and urban green spaces.
And those who live by the sea have better mental health than those who are further inland and do more physical activity in what is known as the "blue gym effect", the analysis said.
The review is led by Defra and UK Research and Innovation, in collaboration with Plymouth Marine Laboratory and Exeter University.
Domestic marine minister Rebecca Pow, said: "Whether it is to enjoy a sport, take a walk, watch the wildlife or to simply admire the landscape, for many of us spending time by the sea is not only hugely enjoyable, but it has a welcome impact on our wellbeing too.
"This realisation makes it all the more important that we take care of our environment, and our ever-expanding national 'Blue Belt', protecting more than 40% of English waters, is helping to safeguard these precious habitats for future generations."
Professor Nicola Beaumont, head of science for Sea and Society at Plymouth Marine Laboratory, said: "Our research demonstrates that marine and coastal areas play an important role in supporting people's wellbeing.
"However, we have also shown that these benefits are threatened by marine pollution, coastal development, climate change and exposure to extreme weather.
"With millions of us visiting the coast every year, it is our collective responsibility to ensure that we have the right measures in place to allow our marine environment to thrive," she said.
Emily Beament is the PA environment correspondent.