"Du Y Moroedd" (Welsh - the black of the sea) is the album of abyssal dark ambient - environmental soundscapes and atmospheres from above by Llyn Y Cwn (Ben Powell), below and beside the ocean; field recordings made onboard vessels at sea; sounds from submerged recording devices deep underwater; recordings from the coasts of North Wales to Greenland and the Arctic Ocean.

The tracks were created onboard the RV Prince Madog whilst conducting research using multibeam sonar to locate, survey and identify shipwrecks from WW1. The multibeam sonar creates images of the seabed using acoustic reflections. It is quite an experience to watch the sonar reveal an unsurveyed wreck and be the first person to "see" the ship for over 100 years; the vessel sitting at the bottom of the ocean waiting in the dark to be discovered. Research into the history of each wreck uncovers stories of boats torn in half by torpedoes and mines, U- boats hunted by destroyers and pummelled with depth charges. Many of these sites aren't just wrecks; they are mass war graves. The vital shipping channel to Liverpool passes the North Wales coast, the U boats would sit and wait; listening. When heard from under the water, each ship has its own unique acoustic signature based on the size of the engine, shape of the propeller, curve of the hull, these acoustic tell-tales were used by the U-boats to identify targets. The shipping lane became a shooting gallery of easy pickings and the submarines were able to slip away undetected into the black of the sea.

The album features recordings from the hull of RRS James Clark Ross whilst ploughing through ice fields off Greenland, from a "sound trap" attached to an anchor as it descended through 80m of water to the seabed, and sounds from onboard the RV Prince Madog with its pitched engine drone. There is also a recording of the bell at Trwyn Du lighthouse, Anglesey, that was made in August 2020, days before the bell was removed to be replaced with a modern fog horn - prior to this, the bell had rung every 30 seconds since 1922" - Benjamin Ian Powell.