Dangerous creatures
Sea
You cannot see a box jellyfish though you easily encounter one. It is transparent. Vinegar is useful not for pouring on the jellyfish but for your painful spot.
https://shimanchu.blog/ishigakijima-marine-hazards/
https://ishigaki-allblue.com/2021/10/23/dangerous-organisms/
Land
Do not let your kids touch an African snail. Do not you touch just to see what happens. There are almost no dangerous drunk people in the island.