Humberside Police have issued safety advice and legal warnings of tombstoning.
The force has reported an increased number of calls in relation to youths and young adults climbing onto the sea wall in order to jump into the sea.
A spokesperson said: "Whilst we understand swimming in the sea can be a refreshing break from the high temperatures, there comes with it the increased dangers of such activity.
"Jumping off the sea wall can result in serious injuries should you collide into the wall or land into the sea in such a position to cause injury.
"There also the dangers involved with the shock of the sea temperature and the strength of the sea currents."
Police have also reminded the public that it is an offence to climb onto the sea wall without a reasonable excuse.
"Climbing onto the sea wall to jump into the sea is not a reasonable excuse. Please can parents be aware of the dangers and legalities involved with tombstoning in order to educate their children mainly to prevent serious harm from occuring."