Single-mode room-temperature cw laser emission on the H13/26→H15/26 2.9 μm phonon terminated electronic transition of Dy3+ is demonstrated. The maximum output power of 0.275 W was generated at a slope efficiency of 4.5% (with respect to the absorbed pump power) when a Dy3+-doped ZBLAN fiber laser was tandem pumped with the ∼1100 nm output from a diode-cladding-pumped Yb3+-doped silica fiber laser.