Mineral filter sunscreens are safe and do not harm the skin or seas. Many chemical filters may be absorbed into your body and can have harmful effects on your skin and the marine ecosystem.

Sailors and the sea exist in a symbiotic relationship. In this regard, a sailor cannot consciously choose a sunscreen with chemical filters.

Oxybenzone - one of the 16 filters approved for use in the USA - is so toxic that just one drop can kill coral which would cover 6.5 Olympic-sized swimming pools.

However, all-mineral filters, like zinc oxide and titanium dioxide, do not harm the marine environment. Look for mineral filters in the active ingredients on your sunscreen bottle - and if you can't see any, then it's time to change.