By Eugene Buchanan

An innovative seal hunter somewhere in the Arctic Circle probably designed the first sea kayak thousands of years ago. Since then it has undergone only a few adaptations. Space-age materials have been joined with stone-age design to offer stability and efficiency even in rough seas. Whether you're buying your own sea kayak or using a rental, choosing one can be as challenging as deciding where to take it. Consider a few things:

Solo or Tandem
Your biggest decision is whether to go it alone and do all the work yourself. Solo crafts are more maneuverable, letting you call your own shots. But their small size makes single boats inherently less stable than tandems. Doubles are faster and provide more storage than a single boat, but be prepared to negotiate with a partner.

Hull Shape
A boat's size and shape determines how it will handle. In general, the longer and narrower the boat, the faster you go (although hull shape plays a role, too). Longer boats also hold a straight course better. Shorter boats are slower and harder to keep straight, but they're easier to turn. Sea kayaks also have what's known as initial and secondary stability. A good choice for beginners, boats with initial stability feel secure in their natural resting position. Boats with high secondary stability are steadier when leaned to an edge. A wide, flat hull is even more stable but will pound more in rough conditions. A deep "V" in the hull makes a boat feel shaky but offers more performance as your skills progress.

Material
Let the waters you'll be paddling guide your choice of a boat's material. Sea kayaks range from polyethylene (molded plastic), fiberglass, and space-age composites to wood and skin-on-frame models. Polyethylene boats are somewhat heavier but can take more abuse than other materials. If you plan to drag your kayak over rocky beaches or paddle in shallow, rocky waters, go with plastic. Fiberglass and composite boats are lighter and faster, but they're more expensive and fragile. Wood boats require more TLC, but they're durable, efficient, and rich with aesthetic appeal. Another option: Build your own wood boat from a kit.

Hardshell or Foldable
If you live close to the water and have ample storage, go with a hardshell (plastic, fiberglass, composite, or wood). If you live a long way from water and don't have storage, a foldable boat might be a better option. These skin-on-frame boats break down into two duffel bags--one for the frame and one for the shell--and can fit inside a closet when not in use. Assembly usually takes no more than a half hour, and the reassembled boat performs nearly as well as a hardshell. They're perfect for traveling: They fit in a car trunk or can be checked as airline luggage. A few hardshell kayaks break down into two, three, and four pieces. These are good for travel too but are generally more expensive than hardshells.

Rudders
Because of their length, tandem kayaks generally come with a rudder for turning. (Consider adding one if it isn't included.) Rudders also help solos stay on course and aid in turning, but they cut into hull speed. Another element to enhance your boat's tracking are skegs, which extend from the rear of the kayak to help hold its course in rough conditions.

Storage Hatches
Hatches allow you to access storage space sealed off by a bulkhead. In the event of a capsize, they also provide buoyancy and water displacement. Some boats offer day hatches with storage right behind the cockpit. Also look for deck rigging to store such accessories as bilge pumps and paddle floats.

Eugene Buchanan, publisher and editor-in-chief of Paddler magazine, is a former kayaking instructor and guide who has paddled on six continents. His articles on the subject have appeared in the New York Times, Men's Journal, Sports Afield, Outside, National Geographic, and other national publications.