5 Worst Summer Travel Dangers

2. Jellyfish
We all have some primal fear of being attacked by sharks in the water, but what about something even more commonplace? Jellyfish exist all over the world, ranging from nearly harmless to extremely venomous. In Australia, a sting from the box jellyfish is so poisonous and painful that victims often go into shock and drown before they can reach shore.

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But most jellyfish stings are easily treatable. If you're stung, clean the area with seawater, followed by vinegar. (One exception, according to the Mayo Clinic, is a sting from the Chesapeake Bay area sea nettle, which responds better to baking soda.)

Leftover stingers can be scraped off by covering the area with a paste of seawater and talcum powder or baking soda and waiting until it dries. After that, ice and common Calamine lotion or other over-the-counter skin cream can help soothe the area.

Seek medical attention if you see swelling or redness over a large area of skin, or if you have a severe reaction like difficulty breathing or nausea.

Next: A year-round, worldwide menace. »