Recommendations for cheap little laptop for Linux in the Grand Canyon

Recently one of my friends won a permit to raft down the Grand Canyon for 21 days, I’m going along rowing one of the boats.

I want to find a cheap little laptop, that is at least semi waterproof / rugged so I can put Linux on it and get data from some of the sensors im bringing (spectrometer, ph, etc), plus do a little programming in the evenings.

It really doesn’t need to be powerful, i would just bring my MacBook but I don’t want to break something expensive.

Secondary objectives are at least reasonable battery life, but not too much of an issue with the solar and batteries we’re bringing.