The Hydro-Pack, received after the mission "Buy Hydro-Pack from Ed" on planet Hoven, is required for this mission. Enter the coolant system by climbing a ladder and entering a tower situated next to the landing pad. Dive into the water, at which point a Gadgetron HelpDesk message will likely tell you to press (or ) to use the Hydro-Pack. You must use it to activate three rings in quick succession to open the gate to the next area, swimming past a few defensive robots identical to spiderbots, except equipped with lasers.
In the next chamber is a pool of electrified water and a lone button in the center. Press it to turn the water safe for travel and start a sixty-second timer, in which you will have to travel through a series of underwater tunnels and chambers, while avoiding lasers and swimming through rings to open locked gates, before the timer runs out. At the end you will find the Bolt Grabber, a useful gadget that increases your range to automatically collect bolts.