 The mudflats and salt marshes outside the seawall are leased by Hampshire and Isle of Wight Wildlife Trust and form their Keyhaven and Pennington Marshes Reserve.Pennington and Oxey marshes are divided into 11 designated Sites of Special Scientific Interest (see Natural England website references 3, 4, 7, 8, 9, 10, 12, 17, 18, 19 and 23).Pennington Common and Upper Common are designated Sites of Special Scientific Interest (see Natural England website references 197, 198, and 199).