The contraflutes of the Metropolitan Flute Orchestra, at Kylemore Abbey in Connemara, County Galway, in the west of Ireland. The three flautists in the front row are holding contrabass flutes tuned in C; behind them are two sub contrabass flutes in G.
There is also a double contrabass flute, which is capable of playing the lowest C on a piano. Its tone sounds even lower, we're told, because flutes have fewer harmonic vibrations than stringed instruments.
To hear a little contrabass fluting and see how the dang things are held and played, try this.