For personnel who are flying over large bodies of water, in additional to wearing a survival suit over cold water, a survival kit may have additional items such as a small self inflating raft to get the aircrewman out of cold or predator infested waters, flotation vests, sea anchor, fishing nets, fishing equipment, fluorescent sea marking dye, pyrotechnical signals, a survival radio and/or radio-beacon, formerly a distress marker light replaced by a flashing strobe, formerly a seawater still or chemical desalinator kit now replaced by a hand pumped reverse osmosis desalinator (MROD) for desalinating seawater, a raft repair kit, a paddle, a bailer and sponge, sunscreen, medical equipment, a whistle, a compass, and a sun shade hat.
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!