Packraft and trail boat are colloquial terms for a small, portable inflatable boat designed for use in all bodies of water, including technical whitewater and ocean bays and fjords. A packraft is designed to be light enough to be carried for extended distances. Along with its propulsion system (collapsible paddles or lightweight oars) and safety equipment (PFD, clothing) the entire package is designed to be light and compact enough for an individual to negotiate rough terrain while carrying the rafting equipment together with supplies, shelter, and other survival or backcountry equipment. Modern packrafts vary from inexpensive vinyl boats lacking durability to sturdy craft costing over US $1,000. Most weigh less than 4 kg (9 lbs) and usually carry a single passenger. The most popular propulsion systems involve a kayak paddle that breaks down into two to five pieces. Most often they are paddled from a sitting position, although kneeling can be advantageous in some situations.