submarining
n.β Β«The seat is also “active”: during a crash the rear section of the raised seat surface automatically sinks in a fraction of a second to prevent the child slipping under the beltβ”submarining,” as it is called in the trade.Β» ββIs new VW kiddyseat the best yet?” Motoring (South Africa) Dec. 28, 2005. (source: Double-Tongued Dictionary)