The dissociation of gas hydrates in sediment pores is thought to decrease seafloor strength potentially facilitating submarine slides because of the generation of overpressured gas and the "melting" of load-bearing or cementing solid hydrate. Here, we present findings that suggest gas hydrates may lead to a previously unknown mechanism of seafloor erosion. Gas-hydrate-bearing sub-sea ridges on the Hikurangi Margin are eroded close to the top of the hydrate stability field in the ocean. We hypothesize that gas hydrate instability may lead to ridge erosion by a combination of two processes; hydrate destabilization caused by depressurization during ridge uplift, and repeated pore volume expansion and contraction from hydrate dissociation and formation triggered by fluctuating water temperatures.