A turbine blade includes a root arranged to attach the turbine blade to a rotor and a vane extending in a radial direction from the root to a tip surface. The vane includes a leading edge, a trailing edge, a pressure-side surface, and a suction-side surface that cooperate to define a vane perimeter. A perimeter wall extends radially from the tip surface and surrounds a portion of the vane perimeter. A first trench wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a pressure-side pocket and a second trench wall extends across the tip surface and cooperates with the perimeter wall to substantially enclose a suction-side pocket.