For many thousands of years people have sailed the sea, as well as taking food and other resources from it. As a result, the seabed is littered with wrecks of ships, submarines and aircraft which can provide a unique source of information on how people have used the sea over the centuries. In addition the sea level has risen, relative to the land, over the centuries, drowning sites that were once on land and preserving evidence of past environments.

Looking for this information underwater has an additional advantage: underwater objects are frequently better preserved than on land. Organic materials, such as wood and leather, will decay quickly if buried on terrestrial sites, but can be preserved for millennia when buried in submarine sediments.

The types of site that can be found underwater can be broadly divided into four categories; wrecks, single finds, structures and submerged landscapes.

In the past two thousand years, 1670 shipwrecks have been recorded as having taken place off the Dorset Coast. The actual numbers of wrecks is certainly considerably higher as, before the nineteenth century, reports are very patchy. They are important for several reasons. First, they provide firm evidence of the history of ship design. Until the eighteenth century, measured plans of ships are very rare, whilst during the nineteenth and early twentieth there was great innovation in ship design and technology, so that wrecks are often the only surviving examples of some types of ship. Secondly, wrecks are 'time capsules', since everything found in a wreck can be dated by the sinking of the vessel. Finds from wrecks can provide valuable information on many subjects, from armament manufacture to dress design.

Single finds are objects which do not appear to be associated with a wreck or structure. They might indicate the site of a previously unknown wreck, they may have been lost overboard, or they may be the result of some other activity. In their own right, they can be of considerable importance, such as the early torpedoes discovered in Weymouth Bay.

Structures are any man-made feature or archaeological site that is now to be found in the intertidal zone, or below high water mark. They include sites built underwater, such as submerged causeways, sites that were built to project above water, but are now underwater, such as old quays and sea defence walls, and sites that were built on land but which are now underwater owing to sea level rise or erosion.

Submerged Landscapes are areas of land that have been inundated by the rise in sea level since the end of the last Ice Age. These areas are important as they may not only provide information about the rise in sea level, but may possibly contain well-preserved organic material.

As the earliest evidence of fishing in Dorset’s seas dates from nearly 10,000 years ago, and the earliest evidence of a shipwreck is over 3000 years old, it is not surprising that there is a great deal of history on Dorset’s seabed.

Gordon Le Pard