Everything really IS bigger in Texas ... just check out Robert Griffin III's massive house on the lake, which just hit the market for $2.6 million, TMZ Sports has learned.
The 7 bed, 7 bathroom crib -- located right on Lake Conroe outside Houston -- is totally tricked out with a game room, theater, wine grotto and wet bar, pool with a swim-up bar and a private dock.
The mansion is located just a few hours from where RG3 grew up in Copperas Cove ... but now that the dude's got a new job in Baltimore, he's ready to part ways with the pad.