Police have launched their biggest operation to control anti-social behaviour in a Pembrokeshire town where the population can increase 10-fold over the summer.
There will be extra officers in the centre of Tenby at weekends, and on the trains coming into the town.
Arriva Trains Wales will also deploy extra security guards.
The idea of Operation Lion is to try to stop some anti-social behaviour before it even reaches Tenby.
It is in its fifth year, but has been getting bigger every time.
The town centre has been a "controlled drinking zone", where drinking on the streets is banned, since 2014.
Insp Aled Davies, of Dyfed-Powys Police, said: "The population of Tenby is normally around 5,000 to 6,000, but in the summer that can go to 60,000.
"Ninety-nine per cent of people who come to Tenby want to come down and enjoy the town as holidaymakers and as visitors, and all we ask is that people who come down here respect the town.
"In the past we have seen a minority of people come to Tenby to visit the pubs and clubs, who then cause trouble due to drinking too much alcohol.
"Behave yourselves, because we will take positive action."
Last year two British Transport Police officers were assaulted and Sgt Steve Dawkins, of the British Transport Police, said it had got out of hand.
"We want to get the message across to keep a clear head, and not let one moment of madness spoil the rest of your life," he said.
"People shouldn't be concerned to see additional police officers on patrol during July and August, which is traditionally an extremely busy time on the rail network.
"Our officers will be on hand to help make sure revellers not only reach the festivities, but also get home again safely."