PocketLab sensors work very well for measuring air and fluid pressure. To protect them, I have students seal them in a ziplock bag along with a paper towel (which absorbs any water that leaks in, keeping the sensor innards dry).
The attached lab worked very well to demonstrate the relationship between fluid column height and hydrostatic pressure. The hardest aspect is modifying the 5 gallon jug by mounting a nozzle connector to its side. It took dexterity, patience, and lots of silicon caulk.