So, the Barbary Corsair has great abilities, and with this bug it can provide unlimited gold. I assume it is reproducible as I was able to do it multiple times, although it was all in the same game. The save file is attached. Variables required: - Be at war with a civ that has built a mountain tunnel on their coast line. - bring your Barbary corsair up beside said mountain tunnel - coastal raid the mountain tunnel - I am not sure if coastal raiding of mountain tunnels is intended, and if so, I'm not sure if it is supposed to destroy said tunnel, but it does not. The Barbary Corsair does not use any movement points for a coastal raid The Barbary Corsair can coastal raid so long as it has movement points Raiding mountain tunnels returns gold You can raid the same tunnel as many times as you want in a turn until you get tired of clicking In the attached save, find the Barbary Corsair parked on the coast of Nan Madol and click away to your hearts content coastal raiding the mountain tunnel.