Two police officers have been forced to resign over claims they took patrol cars on seaside trips while on duty.
The officers were caught on the way to Weston-super-Mare
The Independent Police Complaints Commission (IPCC) said two other Gwent officers were fined and a fifth resigned ahead of the conduct hearing.
Newspapers reported the Pcs were caught when a vehicle broke down on the way to Weston-super-Mare, after previous visits to Barry Island and Porthcawl.
Gwent Police said officers must face "the consequence of their actions".
It was claimed colleagues dubbed the group, four men and a woman, "the seaside five".
The IPCC said the officers have not been subject to a criminal charge.
According to newspaper reports, the unnamed constables dared each other to see how far they could travel away from their station, reaching resorts including Barry Island and Porthcawl - both outside the Gwent force area.
It is understood the matter came to the notice of senior officers after their vehicle broke down while the group had been trying to reach Weston, the other side of the Bristol channel in Somerset.
All four officers at the IPCC hearing were charged with behaving in a way which was likely to bring discredit to the police service.
Three were charged with being neither open nor truthful and one officer was charged with failing to treat a member of the public with courtesy and respect.
IPCC commissioner Tom Davies said: "This investigation has shown that the public can have confidence that the IPCC and the police service will vigorously tackle misconduct.
"Gwent Police has dealt with the officers' behaviour following the IPCC managed investigation and is to be commended for its willingness to tackle a very small number of officers who have abused the trust put in them.
The claims involve use of cars outside the Gwent force area
"I will now ensure that the investigation concludes with a look at management processes within the force to ensure that appropriate lessons are learnt."
The IPCC will not be naming these officers as they have not been subject to a criminal charge.
The officers who were fined will each lose 13 days pay.
Gwent Police said the resignation of one of the male officers last week was not related to the investigation.
In a statement, the force said it did not normally comment on internal matters but was "mindful that the public's confidence in Gwent Police could be compromised by a lack of comment".
It read: "Our officers, just like employees of other organisations, must face the consequences of their actions.
"We will not tolerate any behaviour that falls below the standard expected and required to deliver a top quality service to the public of Gwent.
"As has been demonstrated in this case, any behaviour that threatens this delivery and the public's confidence in the force will be dealt with swiftly and fairly."