Mare Tranquillitatis (Sea of Tranquility) is a progressive solo work for steelpan, crotales, digital delay, and pitch shifter. Over ten minutes long, this work is performed completely in real timea - there are no sequences or pre-recorded sections. Control of tempo and rhythmic accuracy through mixed-meter passages is essential. The performer must be able to play rhythmically and expressively, while controlling steelpan tone quality.