A turbine for extracting kinetic energy from a fluid includes a runner, a turbine-inlet having an entrance and an exit that is adjacent the turbine's runner, and a turbine-outlet having an entrance that is adjacent the runner and an exit. The runner extracts kinetic energy from fluid flowing through the turbine; the turbine inlet directs flowing fluid into the runner; and the turbine-outlet directs flowing fluid away from the runner. When fluid flows through the turbine, the fluid flowing through the turbine-inlet toward the runner flows around and adjacent the fluid flowing through the turbine-outlet away from the runner.