I've tried quite a few sports in my time.

From my experience, the sport with the most nerds is fencing. Nearly everybody there was doing some sort of technical or STEM degree! I know five people in the club I went to were completely obsessed with League of Legends. If you're at university, there might be a fencing club attached the the school. If not, there'll be one in the city. You'll typically be loaned equipment until you decide to buy your own. It might not be outdoorsy, but give it a shot!

There's also LARPing, which is very outdoorsy and is solely populated by very, very nerdy people. I haven't done this myself (because I'm terrible at make-believe), but it could be something that you'll get into. Given the characters I've met who count LARP as a hobby, it's incredibly unlikely that League is not popular in that community.

Search around your city. There are almost always little communities meeting in town halls, dedicated to some kind of niche hobby. I went on a walk once and ended up discovering a circus arts group, for instance (also filled with nerdy people). In the end, it's all up to you. Best of luck!