Apparatus (10) for driving a pile into an underwater substrate, comprises a pile guide (11) having a base frame (12) with a guide member (14) mounted thereon, the guide member configured to guide a pile as it is driven into a substrate when the base frame is resting thereon. The base frame (12) defines a substantially rectangular platform (16) for carrying a device for driving a pile into a substrate, and a power supply for supplying power to drive the device, during deployment. Once deployed, a pile (50) is positioned in the guide member (14) and the device (2) is lifted onto the pile (50). The power supply (30) drives the device (2) as the pile (50) is driven into the substrate.