Flotation Devices
Interestingly, though, I flew with a Us Loco last year in an MD8x. The a/c was not equipped with lifejackets. In the safety demo we were told that the seat cushions were to be used as flotation devices if required.
The airline's network seemed to be nearly 100% over land with only two flights, at that time, over the sea. These were Florida - New England.