Red Mountain is a location on Angel Island.
Eclipse the Darkling and his Dark Arms crash-landed in the Red Mountain Zone following the destruction of the New Black Comet. It briefly served as their dwelling, until Team Dark and Knuckles the Echidna began looking for them. After Eclipse departed the island, G.U.N. forces arrived to remove his ship's wreckage under the supervision of Dr. Julian Snively. (SU: #67, #68, #69, #70