Be generous with the sun block.
You may not notice the sun so much when you’re in the water - but the water will magnify it, and you can get burned without even noticing.
Cover up when snorkelling - your back, legs and bum can get burnt!
Speak to your tour operator if you have any back or neck problems - some smaller boats may not be suitable. They can also advise you on how to minimise the impact of repeated dives.
Keep well hydrated. Working in the sun is tiring and will make you more thirsty than usual.
If you are prone to seasickness, choose a land-based tour with shorter times out at sea. Some regions have rougher water than others. Take medication with you if you are worried - ginger is also a good, natural remedy.
You may spend a long time scanning the ocean - wear good sunglasses with UV protection to save your eyes from the reflective glare. Polarising lenses may also help you see more clearly.
Some regions will require specific vaccinations and other health precautions including antimalarial tablets. Visit your GP 6-8 weeks before departure to seek advice on what you may need.
Some marine conservation trips are based in very remote locations and could be some distance from hospitals or healthcare facilities – it’s advisable to bring rehydration sachets, medicine for stomach upsets, a basic first aid kit and some antiseptic cream for any cuts, which can become infected easily and heal slowly when exposed to water.
Check the CDC website for up-to-date health advice for your destination.