A method for replacing a first control pod (30, 30') of a BOP stack, the method comprising: (a) lowering a control pod exchange device subsea with a second control pod (30, 30") positioned on the control pod exchange device, wherein the control pod exchange device comprises: a housing including a first bay, a second bay horizontally adjacent the first bay, and a third bay horizontally adjacent the second bay, wherein the second bay is horizontally positioned between the first bay and the third bay, wherein each bay (212a, 212b, 212c) is sized to receive the first control pod (30, 30') or the second control pod (30, 30") from the BOP stack and transfer a second control pod (30, 30") to the BOP stack; a control pod transfer assembly moveably disposed in the housing, wherein the control pod transfer assembly is configured to move the second control pod (30, 30") horizontally from the first bay to the second bay and move the first control pod (30, 30') horizontally from the first bay to third bay; (b) coupling the control pod exchange device to the BOP stack; (c) transferring the first control pod (30, 30') from the BOP stack to the control pod exchange device and transferring the second control pod (30, 30") from the control pod exchange device to the BOP stack while the control pod exchange device is coupled to the BOP stack, wherein (c) comprises: receiving the first control pod (30, 30') from the BOP stack into the second bay with the second control pod (30, 30") in the first bay; moving the first control pod (30, 30') laterally from the second bay to a third bay after; moving the second control pod (30, 30") laterally from the first bay to the second bay after; and moving the second control pod (30, 30") from the second bay to the BOP stack after; (d) decoupling the control pod exchange device from the BOP stack after (c); and (e) lifting the control pod exchange device and the first control pod (30, 30') disposed thereon to the surface after (c) and (d). (a) lowering a control pod exchange device subsea with a second control pod (30, 30") positioned on the control pod exchange device, wherein the control pod exchange device comprises: a housing including a first bay, a second bay horizontally adjacent the first bay, and a third bay horizontally adjacent the second bay, wherein the second bay is horizontally positioned between the first bay and the third bay, wherein each bay (212a, 212b, 212c) is sized to receive the first control pod (30, 30') or the second control pod (30, 30") from the BOP stack and transfer a second control pod (30, 30") to the BOP stack; a control pod transfer assembly moveably disposed in the housing, wherein the control pod transfer assembly is configured to move the second control pod (30, 30") horizontally from the first bay to the second bay and move the first control pod (30, 30') horizontally from the first bay to third bay; a housing including a first bay, a second bay horizontally adjacent the first bay, and a third bay horizontally adjacent the second bay, wherein the second bay is horizontally positioned between the first bay and the third bay, wherein each bay (212a, 212b, 212c) is sized to receive the first control pod (30, 30') or the second control pod (30, 30") from the BOP stack and transfer a second control pod (30, 30") to the BOP stack; a control pod transfer assembly moveably disposed in the housing, wherein the control pod transfer assembly is configured to move the second control pod (30, 30") horizontally from the first bay to the second bay and move the first control pod (30, 30') horizontally from the first bay to third bay; (b) coupling the control pod exchange device to the BOP stack; (c) transferring the first control pod (30, 30') from the BOP stack to the control pod exchange device and transferring the second control pod (30, 30") from the control pod exchange device to the BOP stack while the control pod exchange device is coupled to the BOP stack, wherein (c) comprises: receiving the first control pod (30, 30') from the BOP stack into the second bay with the second control pod (30, 30") in the first bay; moving the first control pod (30, 30') laterally from the second bay to a third bay after; moving the second control pod (30, 30") laterally from the first bay to the second bay after; and moving the second control pod (30, 30") from the second bay to the BOP stack after; receiving the first control pod (30, 30') from the BOP stack into the second bay with the second control pod (30, 30") in the first bay; moving the first control pod (30, 30') laterally from the second bay to a third bay after; moving the second control pod (30, 30") laterally from the first bay to the second bay after; and moving the second control pod (30, 30") from the second bay to the BOP stack after; (d) decoupling the control pod exchange device from the BOP stack after (c); and (e) lifting the control pod exchange device and the first control pod (30, 30') disposed thereon to the surface after (c) and (d).