Sea lanes are also known as shipping lanes, as they are routes through the oceans of the world that vessels use to move cargo and facilitate trade. Each sea lane is typically designed to take advantage of a current or a prevailing wind to decrease travel time. In certain cases, a sea lane may deviate from favorable currents or winds in order to service important trade cities. Due to the presence of very large vessels, a sea lane can be a dangerous place for divers, pleasure crafts, and other small boats. Shipping lanes can also pose a danger of piracy, as the regularity with which vessels pass through particular waters can make them easy prey.
The first sea lanes were established during the age of sail, when vessels depended on prevailing winds to circumnavigate the globe. These sea lanes were not official, though ships did tend to take similar paths to take advantage of winds. Ocean voyages could be long and dangerous, so sticking to an established sea lane with known trade or westerly winds could contribute to the ultimate survival of a vessel. Many ships would take southern courses when traveling from Europe to North America, and then assume northern routes when returning in order to make use of known prevailing winds on each leg of the journey.
When steam ships took over as the primary means for moving cargo across the oceans, winds became less of a concern. It was possible for self-powered steam ships to ignore winds and currents, though these factors could still provide benefits. Many shipping lanes were established due to prevailing winds and favorable currents to reduce travel times and fuel expenditure. It takes less effort to move with a current than against it, and winds can also create waves that may be used to a vessel's advantage.
Modern shipping lanes are used by a vast worldwide fleet and are typically some of the most populated areas of the oceans. Despite being relatively empty due to the enormity of the oceans in comparison to the number of vessels in use, a sea lane is typically one of the more dangerous places for a small boat to be. Even a relatively minor collision with a much larger shipping vessel could capsize a small pleasure craft, and similar dangers can be posed to divers.
A sea lane may also provide a possible avenue of rescue to a small vessel in distress. The chances of happening across another vessel in the open ocean are incredibly low, so if a damaged pleasure craft can limp to a sea lane, the hope of rescue may increase. If a small boat is in danger of sinking or in any other form of distress, the dangers associated with sea lanes can easily be outweighed by the potential for rescue.