I've carried my enduras at the beach since I've bought them in around 92. They have also been in rivers, lakes, and swimming pools. If anyone ever noticed no onew ever said anything to me about it. I typically don't invite conversation though. When I'd get back from the beach a good rinse in fresh water, dry on papertowels and blown out. A blast of break free clp followed by a wipedown again, working the action of course.
The only rust issues I've ever had was in can cun with a cheaper knife than a spyderco that I brought in case of confiscation. The rust was mainly in the pivot area, though the blade did rust a bit. This was a "surgical steel" knife, not my G2, then ATS 55, now VG10 Spydercos. They've all been to the atlantic, and mexico . They usually come up gritty though and need some work. Joe