The number of new melanoma skin cancer cases diagnosed in a year has risen above 20,000 for the first time in the UK.
The charity Cancer Research UK says too much exposure to ultraviolet (UV) light from the sun or sunbeds is part of the cause, with an estimated nine in every 10 cases thought to be avoidable.
It is possible to prevent skin cancer by being careful in the sun, by using sunscreen with at least SPF 30 and four or five stars, and seeking shade.
Anyone can get sunburn, including people with darker skin tones, and the charity is reminding the public to stay safe over what could be a sunny bank holiday across much of the UK.
Sunburn is a clear sign your skin has been damaged, although you do not need to burn—or even turn pink—to sustain skin damage.
The chief executive of Cancer Research UK, Michelle Mitchell, said: "Take care when the sun is strong by seeking shade, covering up and applying sunscreen and, if you notice any unusual changes to your skin, contact your GP.
"Whether it is a new or changing mole, a sore that doesn't heal, or an area of your skin that looks out of the ordinary, it's important to get it checked out.
"It probably won't be cancer, but if it is, getting it diagnosed and treated early can make all the difference."
The charity's analysis of the most recent full data, for 2022, shows there were 20,980 new cases of melanoma in the UK - the highest number it has seen for the deadliest form of skin cancer.
Women are more likely to be diagnosed with melanoma at younger ages because of more sun exposure, including sunbathing and sunbed use.
Rates are higher in men in later age, linked to long-term sun exposure.
Cancer Research UK says overdiagnosis - when cancers that would not go on to cause harm are identified - could also be playing a role in rising rates, alongside increased awareness.
Under-18s are already barred from using sunbeds, but teenagers can sometimes dodge the rules by using contactless payment systems that let you tap and tan without any checks by a staff member, warns the government.
New rules - for mandatory ID checks that would require staff to review customer details to stop any children from using sunbeds - are being considered.
Public Health and Prevention Minister, Sharon Hodgson, says: "Sunbeds cause cancer - and yet children as young as 14 are still accessing them illegally. That is not acceptable.
"We're closing the ways in which businesses could get away with this, and making sure anyone who uses a sunbed knows exactly what they're risking."
Mother-of-two Rebecca Dance, from Berkshire, was diagnosed with malignant melanoma aged 39.
She noticed a suspicious mole on her back and was referred by her GP to hospital, where it was removed.
Now aged 44, she says she believes the surgery saved her life. The cancer was caught at the earliest stage before it had chance to spread.
Melanoma is the most serious form of skin cancer and, untreated, can be deadly.
"My whole life flashed in front of me because I just thought, 'Oh my God, I've got cancer.'
"I was in complete shock. I knew what melanoma was and that it was the worst type of skin cancer that can spread to your organs," she told BBC News.
"I tried to live life as normal as I could between the diagnosis and surgery, but it was weighing on my mind. I'm a single parent and my worst fear was dying."
She says there is a misconception that skin cancer only happens to people who use sunbeds or sunbathe.
"I've got very pale skin and a lot of moles so I am at higher risk already. I'm always really careful in the sun.
"The sun makes people happy - of course it does. But I'll always be extra careful, use factor 50 suncream and cover up."
She advises people to regularly look for any skin changes and get them checked: "Don't delay speaking to your GP if you notice anything."
To be safe in the sun, Cancer Research UK recommends people:
