Find a pump | Chapter 5 - Pump Action DI Riptide Guide

Jimmy's Workshop, about which he mentioned is in already visited Marika's Marine. You can get there on your own, but it's better to use Fast Travel (map in the ruins).

When you get nearby the workshop, go through the river, but beware of Floaters. What is more, this area should be guarded by a Drowner and Suicider. Defeat them from a safe distance.