If pool swimming and taking a pool shower afterwords counts, then once a day. If not, every other day. But, if i get really sweaty, or dirty, at least one shower a day, if not two.
Once, in the summertime when I was a teenager, i held a record for ten days without an official bath or shower. It was ocean surfing all morning and day, then shower off at the beach showers. I didn't stink, so what did I care? I had to stop and take a shower because my hair was dry and severally damaged from not washing it, that I had to shower. Plus, I wanted to ask this girl out, and couldn't go looking like a homeless surf bum.