flashlight

Ah, magnetic charging tail caps. To charge the battery, electricity must be able to flow to the battery via the tail cap. Unfortunately, a lot of earlier/cheaper implementations accomplished this via a direct connection, which didn't prevent current from leaving the tail cap should it short against something (steel wool, water, etc), although the usual suspects like coins were usually not physically able to make contact with the recessed center pin.

There was quite a kerfuffle about it. Thanks to people like Zak, olight issued replacement tail caps that contained a protection circuit, likely a diode, to prevent this.

https://www.reddit.com/r/flashlight/comments/6lk901/olight_h2r_ignites_steel_wool_with_its_tailcap/

https://www.candlepowerforums.com/threads/olight-h2r-nova-quick-review-new-improved-tailcap-available-now-see-post-32.436167/

You may have to look at reviews to see if the light you're considered includes protection. As for salt water, it is what it is there. Give your lights a good rinse when you're back home in the sink and don't worry too much about it.