At low tide the Thames Foreshore is a remarkable combination of beach and archaeological site. For example, the Londonist website explains that a tour of the Rotherhithe foreshore with the Thames Discovery Programme is likely to produce Georgian clay pipes, Blitz rubble, and even evidence of prehistoric Londonders.
The Thames foreshore is administered by the Port of London Authority. Anyone wishing to search the tidal Thames foreshore in any way for any reason must hold a current foreshore permit from the Port of London Authority, for which a charge is made. Searching is defined to include metal detecting, digging, and scraping. There are two types of permits: Standard (allows digging to a depth of 7.5 cm) and Mudlark (allows digging to a depth of 1.2 m). The Mudlark permit is issued only to members of the Thames Mudlark Society. To become eligible to join the society applicants mush have held a Standard permit for two years, and must have a reporting finds to the Museum of London.
There is no charge for walking on the foreshore. The areas of the foreshore to which access is permitted are shown in maps on the Port of London Authority websites, which is linked to below.