There are extensive bog gardens, home to "giant rhubarb" (Gunnera manicata) and American skunk cabbage.
The gazebo to the right of the castle was built by the Admiral to view the incoming ships as they entered Swansea Bay, and is surrounded by a stand of Monterey Pine 'Pinus radiata'.
These trees have retained their lower branches which filter the prevailing winds and give greater cover (protection) to the area.
The water which rises in Clyne Common travels under the Japanese Bridge and through the gardens to join the sea at Blackpill.
Glynn Vivian planted three notable trees still alive in front of the castle: one Wellingtonia 'Sequoiadendron giganteum' and two Monterey Cypress 'Cupressus macrocarpa', one a fastigiate form which is also one of the tallest recorded in Britain.