I used to spearfish and freedive when I was in Okinawa and the first lesson I learned is, the water will be cool enough to mask the suns rays being magnified onto your back. Red turned bright red, then turned to little blisters, which then turned to one big blister that burst with enough liquid in it to soak my pants, underwear, and then down into my boots. I was sick with sun poisoning for days. Spearfishing is cool if you know what the areas dangers are, ( tides, currents, toxic fish/jellyfish,etc.) Talk to folks at the local dive shop or locals when you hit the spot. I was spearing one morning and had taken a few good sized fish and everything was cool until the blood from the fish attracted a shark. ( Do not clip the fish to a belt, use a bag on a float.) Wear a shirt or good water proof sun screen when diving, and keep your head on a swivel. You can get focused on what is right below you, get into a strong current, and not notice 'till you are far away from where you want to be.(be aware of changes around you.) If you use common sense and don't go alone, you will be fine.