>>2507282If he hikes, buy him a nice Thermarest self-inflating sleeping pad. Even if he already has one, he'll eventually need another, or he can alternate to share wear and tear between the two. It's the one thing just about every hiker wants or can use.
If he fishes, get him a gift card to Bass Pro, Cabela's, Tackle Warehouse, Simms/Orvis, etc. If you don't fish yourself, then you have no way of knowing what he'll want.
If he hunts, same deal. Get him a gift card.
I mean there are gifts any fisherman or hunter would appreciate, but they're expensive, and I know from long experience that a woman won't buy expensive gifts for a man unless she's a cougar sugar mama. So those are pretty much off the table.