Can you get sunburnt underwater?
A lot of people don't apply sunscreen before swimming, but is this necessarily a good idea?
UV-B, the frequency range of ultra-violet light that causes sunburn, is absorbed by water but you need a few metres of it to provide adequate protection.
Half a metre of water will still let 40 per cent of the UV-B through and the cooling effect of the water makes you less aware of the Sun. Burning your back while snorkelling is very easy to do.
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