What is 29,000 years old, 54 miles long and supplies most of Tampa's potable water? The Hillsborough River, of course! To conclude a week-long celebration of the river's watershed, government and nonprofit groups present "A River Runs Through It" Outdoor Expo, which brings together vendors, musicians and outdoor enthusiasts in an effort to showcase the Hillsborough River State Park's recreational activities. Under the shade of sprawling oak hammocks, youth and adults can commune with nature via canoe and tram rides, and enjoy workshops and exhibits on the local environment, Florida-friendly landscaping and the wildlife that makes this part of Hillsborough their home. Sat., Oct. 27, 11 a.m.-5 p.m., 15402 U.S. 301 N., Thonotosassa, free admission, 813-987-6771, hrwa-fl.org.