Watercraft are easier to retrofit to alternate propulsion than cars. While the width of roadways is rather fixed, ships can be built with a greater beam or deeper drafts could be built to accommodate battery cells and other alternate propulsion means - up to and including nuclear reactors in many larger military craft. Sail power for personal craft is common, but most commercial loads would be impractical for standard sails. However tethered "kites" that hold wind turbines in the slipstream several hundred meters above the ship can provide plenty of electricity.
Despite the efficiency and available power, the use of boats and ships is highly situational in the US anarchy zones. On one hand, many of the cites were built near major bodies of water as a legacy of being settled before the construction of the interstate system. However the many sets of river locks, levies, and other products of the civil engineering corps that contributed to the ease of navigation along the waters have degraded.
Large ships require a lot of dockyard maintenance for everything from rest prevention to the multi-ton engine gears. No transit and limited manufacturing mean that most large ships are stuck where they are moored. However, this has been turned into a boon, as a an old cruise ship can make for a very nice and defensible base of operations, with several miles of ocean separating it from reanimates.
Reanimates have been observed swimming to cross obstacles. Their unusual biology should allow them to survive being underwater for several minuets longer than a human could. However, they are often reluctant to enter water. Kappas/Epsilon types have far too many integrated pieces of metal to be buoyant, type ones lack the coordination to do much more than dog paddle, and alphas have too much a sense of self preservation to enter dangerous situations from the water. Twos and Betas on the other hand, love to ambush from the water like crocodiles.
Reanimates are not the only danger at the water's edge. The populations of alligators, aquatic snakes, bears, crocodiles, and other predators have exploded in recent years. Previously, Human activity was a major check on populations as they either competed for prey split up habitats with construction, accidentally killed large numbers of animals with pollution and occasionally actively destroyed the large predators. Without the regular spraying of pesticides, disease carrying pests like mosquitoes have also become a much larger problem near water.
Europe has a slightly different problem with aquatic transit. Most notably, the Baltic, North Sea, and occasionally the English channel are patrolled by members of the Kola Command Authority. In turn, anything larger than a rowboat risks being run down by a nuclear powered cruiser or ambushed by fuel cell equipped diesel-electric submarine, and held for ransom. Major rivers might occasionally see an ekranoplan or missile hydrofoil representing the KCA, but are much safer, if not leading quite as far.
The disposition of the world's navies will be discussed in a later article.
Taking to the Air
Ultralite aircraft are a popular choice for long distance travel and exploration. While the necessary power to weight ratios require liquid fueled engines, once the appropriate supply has been manufactured or obtained they can bypass many roadblocks. Many craft in this style are easy to maintain, and to disassemble which has become even more important. After-all, its the best way to keep such a valuable piece of equipment safe - either keep it in the shelter with you, or remove a few key parts to prevent others from absconding with it.
Long stretches of abandoned highway have made for plenty of stopping points for civil aircraft. However, the requirements for maintaining them means that there are thousands of planes that are simply rotting away in hangers and on tarmacs. Much the same applies to agile but fuel hungry helicopters may be agile, and multi-surface inflatable skirt hovercraft.
However, two seemingly dead aviation technologies have witnessed a renaissance.
Zeppelins made a rather surprising comeback in the mid 2030s. Although lighter than air craft often rather slow, they are more efficient fuel wise than jet aircraft, and can hover in one place longer than helicopters while maintaining higher altitudes. They are used for long range patrols, mobile cranes, or in the role of cruise liners for multinational trips. Despite the Hindenburg disaster that ended the first era of airships, many modern zeppelins use hydrogen - its cheaper than Helium, has a greater buoyancy, and can be manufactured on site, while modern materials and safety systems mitigate its flammability risk. Several dirigibles are still airworthy because their main requirement can be easily manufactured, and their low speeds allow for simpler and more robust engines. Of course booking passage on one these days is more likely to invoke a quest of Tolkien-esq proportions than booking with a local agent.
Wing in ground effect vehicles - also known as ekranoplans - became rather popular means of transit for situations where higher speeds were required. The infamous 550 ton Caspian sea monster was able to travel at high speeds low over the water with 1960s technology. Modern composites, better engines, and computer aided design coupled with the efficiency of flying in ground effect made them quite desirable when oil shortages rendered conventional jumbo-jets exceedingly expensive to use. Furthermore, these low flying boats needed to a body of water, rather than expanding already overburdened airports.