Cheap G-Shock will do you, just don’t expect to be completely indestructible.
Watches
A community for watch & horology discussion.
Casio Duro
G-shock is well liked by the watch community and is well known to be hard to destroy. You'll see them on soldier's wrists and also see them in rich man's watch collection.
The classic g-shock model is the DW5600, and you can find variation of that model under and around 100 USD.
Casio Mrw 200
Salt water, sweat and sun will destroy your G Shock. It did mine. I got a much cheaper 100m Casio W800H, and it's on sale at Amazon for $15 right now. I won't be as bummed when the resin case starts to deteriorate. This is my beater beach, yard work, and pool watch. I got these 3 for $120 combined all on sale during the holiday' over the last 3-4 years. If I got the regular G shock (not solar atomic), combined cost would have been $90. If you take your time shopping and hold out for sales, you might be able to get 3 watches within your $100 budget.
Not g-shocks - too bulky so they get caught/knocked on stuff and they've got shit legibility. And the plastic straps are sweat traps. And the buttons are a pain in the tits.
Casio MW600F-1AV and HDA600B-1BV are both inexpensive analog watches with 100m water resistance, and 10 year batteries.
If you have smaller wrists the Casio mtd1053 (40mm) is smaller than the Casio Duro and has the same specs.
If you are in the US you could take a look at the officialwatchdeals store on ebay.
Get this eco-drive field watch bm8180 if you want something small. It's worth the money and it's solar powered.
If you want a diver get the bn0151, bn0158 or bn0150. It's definitely worth the extra $50. These are ISO certified divers 200m watches and have been individually tested to meet that standard. These are robust and wear smaller than their size would suggest.