The Solent is a major shipping route for passengers, freight and military vessels. It is an important recreational area for water sports, particularly yachting, hosting the Cowes Week sailing event annually. It is sheltered by the Isle of Wight and has a very complex tidal pattern, which has greatly benefited Southampton's success as a port. Portsmouth lies on its shores. Spithead, an area off Gilkicker Point near Gosport, is known as the place where the Royal Navy is traditionally reviewed by the monarch of the day.
The area is of great ecological and landscape importance, particularly because of the coastal and estuarine habitats along the edge of the Solent. Much of its coastline is designated as a Special Area of Conservation. It is bordered by and forms a part of the character of a number of nationally important protected landscapes including the New Forest National Park, and the Isle of Wight AONB.
Originally a river valley, the Solent has gradually widened and deepened for many thousands of years. The River Frome was the source of the River Solent and two other rivers called the Itchen and Test were tributaries of it. Remains of human habitation have been found from the prehistoric, Roman and Saxon eras, showing that humans retreated towards progressively higher ground over these periods. However, there is a new theory that the Solent was originally a lagoon. This theory was reported in the Southern Daily Echo by Garry Momber from the Hampshire and Wight Trust for Maritime Archaeology..
There is an early Norman period report that much land on the south of Hayling Island was lost to sea flood. South of Hayling Island in the Solent is a deposit of stones, which scuba divers found to be the remains of a stone building, probably a church. There is an old report that this church was formerly in the middle of Hayling Island. If similar amounts of land have been lost on other parts of the Solent shore, the Solent was likely much narrower in Roman times, and it is possible to believe Julius Caesar's report in De Bello Gallico that in his time men could wade to the Isle of Wight at low tide. Similarly, it is known that Selsey was once a port town, with an Abbey and Cathedra recorded until 1075, when the see of the Diocese of Sussex was moved inland to Chichester.
During the late Middle Ages, Henry VIII of England built an extensive set of coastal defences at each end of the Solent, part of his Device Forts, effectively controlling access to east and west. More forts were built on land and at sea in the 19th century. These were generally known as Palmerston Forts
In 1982 Henry VIII's flagship, the Mary Rose was lifted off the sea bed of the Solent, 437 years after it sank.
A bank in the centre of the Solent, Bramble Bank, is exposed at low water springs. This, combined with the unique tidal patterns in the area, makes navigation challenging. There is an annual cricket match on Bramble Bank during the lowest tide of the year, although games are often cut short by the rising tide.
Sea bed survey shows that when the sea level was lower in the Ice Age the Solent River continued the line of the eastern Solent (Spithead) to a point roughly due east of the east end of the Isle of Wight and due south of a point about 3 km west of Selsey Bill, and then south-south-west for about 30 km, and then south for about 14 km, and then joined the main river flowing down the dry bed of the English Channel.
Ten thousand years ago a band of relatively resistant Chalk rock, part of the Southern England Chalk Formation ran from the Isle of Purbeck area of south Dorset to the eastern end of Isle of Wight, parallel to the South Downs. Inland behind the Chalk were less resistant sands, clays and gravels. Through these weak soils and rocks ran many rivers, from the Dorset Frome in the west and including the Stour, Beaulieu River, Test, Itchen and Hamble, which created a large estuary flowing west to east and into the English Channel at the eastern end of the present Solent. This great estuary ran through a wooded valley and is now referred to as the Solent River.
When glaciers covering the north of Britain melted at the end of the last ice age, two things happened to create the Solent. Firstly, a great amount of flood water ran into the Solent River and its tributaries, carving the estuary deeper. Secondly, post-glacial rebound after the removal of the weight of ice over Scotland caused the island of Great Britain to tilt about an east-west axis, because isostatic rebound in Scotland and Scandinavia is pulling mantle rock out from under the Netherlands and south England: this is forebulge sinking. Over thousands of years, the land sank in the south (a process still continuing) to submerge many valleys creating today's characteristic rias, such as Southampton Water and Poole Harbour, as well as submerging the Solent. The estuary of the Solent River was gradually flooded, and eventually the Isle of Wight became separated from the mainland as the chalk ridge between The Needles on the island and Old Harry Rocks on the mainland was eroded. This is thought to have happened about 7,000 years ago.