I just bought a home with hardwood floors everywhere, including the bathrooms. While this is nice, I worry that they will be damaged by constant exposure to water. Is there anything I can do to protect them, besides high quality bath mats?
Wood constantly moves by expansion and contraction which varies with humidity and moisture. There is no "sealant" that I know of that would prevent this natural movement and the cracks between the planks from opening and closing as a result. Wax will protect the surface finish, but make them slippery unless you use a non-slip formula.
The only recourse is to use bathmats (as you've already identified) and wipe up the floor if you should splash water on them. Just be careful with the combination of cloth bathmat and waxed floor. Also be careful of leaving rubber backed bath mats on the floor finish. Some may change the sheen of the floor (dull it) and leave an outline of the mat/rug.
This is a good one. I find that rather than just getting a bath mat, it might be best to get a large piece of rubber that can be placed under the mat to keep it in place. It may also help to cover your floor with a strong varnish or something like wax, this can help keep the floor better for longer and protect from thing like water.