The RNLI is reminding people that Tombstoning is particularly dangerous as water depth can be unpredictable and alter with the tides.
The water may be shallower than the jumpers think and there are often hidden objects on the seabed.
Other dangers include the shock of cold water and unanticipated currents.
Brighton RNLI Lifeboat Operations Manager Roger Cohen MBE said : ‘Jumping from piers and groynes, known as tombstoning, can be incredibly dangerous at any state of the tide for a number of reasons such as submerged rocks and strong currents.
‘We realise that it’s tempting to jump from height into the water, especially with such great weather but submerged items may not be visible and could cause serious injury if you hit them.
‘The shock of cold water may also make it difficult to swim and in some places strong currents might sweep you away.’
The RNLI recently issued a warning saying: ‘Whilst we’d never advocate people jumping from height into the water, if they do, there are things to consider to reduce the risk of injury.’ They said people should take precautions and consider the following: Water changes depth with the tide, so the water may be shallower than it looks Submerged items may not be visible and can cause serious injury or paralysis if you hit them The water can be a lot colder than it looks so the shock of cold water may make it difficult to swim Always check for hazards in the water like submerged rocks People should never enter the water while under the influence of alcohol, drugs or peer pressure Important to check for access because it may be impossible to get out of the water Coasteering with a registered company is a safer alternative The RNLI is also urging anyone visiting the coast this summer to make sure they keep themselves and their families safe.