If there's a single landscape near Ankara that begs to touched, felt, and seen, it's the geological oddity known as Lake Tuz. One of the largest salt lakes in the world at over 1500 square km (580 square miles), the lake is the center of industry in the region that exists between the cities of Konya and Ankara, producing an incredible two-thirds of the salt consumed in Turkey.
A protected area since 2001 due to the fragile and unique ecosystem that supports creatures like the Greater Flamingo and Greater white-fronted goose, this body of water is an interesting visit during all seasons. In winter months the lake is quite shallow and can be waded in (although we strongly suggest wearing some sort of waterproof footwear), while it can completely dry up in the summer heat, leaving a hard crust of salt for travelers to walk on. There aren't really any official hikes, but it is worth trekking out to Büyükada Island, where a Romanesque church still stands.
Tours to Cappadocia will often stop here, which can work as a one-two punch if you're trying to cross a bunch of activities off of a list, but transportation along the E90/D750 would otherwise be the way to go for the independent traveler. Even if it's to get a few pictures wandering a salt vista that stretches to the horizon while also lingering to taste locally-grown fruit in a nearby market, a few hours at Lake Tuz can prove to be an interesting part of your Turkish adventure.