Do I need to find some sort of waterproof key container ?

I have plain jane copies of my house key and my jeep key. I get dog
tag chains from the army navy for $1.80, or something. I don't put
both keys on one chain - I have a house key chain and a jeep key
chain. I can go running, biking, hiking, fishing, whatever, either
from the house or the vehicle, and just throw the appropriate chain
around my neck and it's all good. If, for some reason, I'm paranoid
about getting my neck ripped off, I put the key/chain in a ziploc (the
old-fashioned kind, not the kind with the little slider device) and
then tuck it into my chest pack. I'm extremely minimalist, I just
take a *tiny* chest pack when I fish, and the key/chain is so small
that I don't notice the room it takes up. But usually I just wear it
around my neck. I leave the regular key set in the jeep.