What are you afraid of this summer?

From low water levels to Middle East volatility, here's what's keeping travelers awake at night — and what to do about it

Jan Howell is afraid of the water levels this summer.

She's booked on a Danube riverboat cruise, and she's concerned that the water won't be high enough for the ship. That could turn her cruise into a bus tour — or even cancel it. Months of careful planning would go down the drain.

"That's my biggest worry," says Howell, a nurse from Spokane, Wash.

This su…