Hoy, Lyness, Former Diesel Engine Pump House

The former Diesel Engine Pump House at Lyness, built around 1938, is a tall, six-bay gabled structure that is part of a significant group of military buildings located next to Scapa Flow. It features a perpendicular gabled extension to the east and a separate raised metal water tank to the west. The building is primarily constructed with a steel frame and has rendered brick walls, along with a thickened concrete base course up to cill height. The north and south elevations each have three bays and a blind oculus in the center bay, with multi-pane metal windows that include hopper openings.

Inside, which can be accessed through doors on the west and north elevations, the space is divided into two areas: a boiler room and a pump room. As of 2013, most of the machinery necessary for pumping oil, including engines, boilers, and pumps, remains in place.