Dolphins and porpoises living off the coast of Peru face daily threats: industries expanding into their native waters and a lucrative poaching trade. To help, Smithsonian researchers need to study at least three species—namely, the bottlenose dolphin, the elusive dusky dolphin and Bermeister’s porpoise—that have been spotted near a busy maritime port. With two acoustic instruments and a hydrophone, they plan to record the animals’ underwater sounds, gauging how they’re impacted by maritime infrastructure, as well as identifying other species in the area. The sensors only listen, so they’re safe for marine mammals. This project will help scientists provide guidance to those living and working on the water about how best to coexist with these animals, giving them the best chance to rebound.