Police were called to investigate an incident at Anglesey Sea Zoo on Saturday afternoon after a man threatened to burn the place down.
Staff at the North Wales attraction say the man repeatedly punched a wall and abused workers with horrific terms.
The man was described as around 6ft with tattoos, in his 20s or early 30s and had a strong Liverpool accent - North Wales Live reports.
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The owner of Anglesey Sea Zoo says the incident escalated after he made a complaint about site safety.
Frankie Hobro said: "We have never had something like this, this person was clearly out to make trouble.
"This is the fourth incident in recent weeks where our staff have been subjected to an unreasonable level of verbal abuse by visiting members of the public, although this is the first incident which is serious enough to be reported to the police, as we fear that the individual concerned is currently visiting the area and is capable of inflicting real harm."
Frankie was off-site when the incident happened, but says the complaint arose after the man feared his daughter had been in potential danger as some areas of the site were not blocked off.
She said while there is work being carried out at the site at this time there are clear signs and ropes to ensure people stay safe.
The owner of the zoo said a female member of staff in her 20s offered a refund - but the visitor responded aggressively.
Frankie said: "He was f-ing and blinding. There were customers having to take their children away because it was so unpleasant."
Staff claim he said "I'll lamp you and burn this place down" at one point before they phoned the police.
The confrontation was only diffused when a male member of staff became involved and the man was informed his behaviour had been reported to the authorities.
Frankie said: "This was really upsetting and unnecessary and very frightening for staff. Why be so horrible?
"The man was clearly in the area on holiday and my worry is that he could repeat this behaviour somewhere else.
"We respectfully remind everyone that abusive or threatening behaviour will not be tolerated for any reason, and that we reserve the right to ask anyone exhibiting unreasonable behaviour to leave the premises, or to call the police to have them removed.
"We ask people 'be nice - everybody is doing their best'. It has been a difficult time for everyone."
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