Thanks! That's exactly how it works over here. The act of trespass is not a criminal offence but as soon as you cause damage to gain entry you have committed criminal damage. A land owner can take a trespasser to a civil court but it's unlikely he would be awarded damages unless the act caused some sort of disruption.
There's a site in north Wales called
Dorothea. It is a disused slate quarry which filled with water when it shut and the pumps were turned off. It is a beautiful site and a great dive. It unfortunately suffers from sensationalist news reports and opposition as a dive site from locals due to a number of deaths. It is just over 100m (330 ft) at its deepest point but there are shelves at much shallower depths which are within easy reach of recreational divers. There are submerged buildings and a tunnel at 22m (72 ft). The tunnel is large enough to swim through side by side and is also quite short, making a pretty safe swim-through. There is another tunnel at 57m (187 ft) that is a bit tighter and obviously outside recreational limits.
It is as safe as any body of water but people push their limits and get into trouble. A mate of mine has dived the 57m tunnel on air with a single 15 litre cylinder and a 3 litre pony. I've told him on several occasions he's mad, but he is totally unconcerned. He said the pony will get him to the surface. I asked him if that is at a sensible ascent rate and inclusive of deco stops. He said he'd probably end up in the chamber,
"or paralysed, or dead", I added. Recently I saw his pony in his car boot, complete with the reg. I noticed the reg looked a bit cheap and nasty. There were no manufacturer's logos and I asked what it was. He said he didn't know - he bought it off Fleabay and doesn't know its history, whether it's ever been serviced or whether it's cold water rated (temperatures of 4°C are common at depth, even in the summer).
There have been attempts to turn it into an organised dive centre but they have never been a success. There have been attempts to block access but this has been a problem as the roads are used for access to land. I believe the owner once tried to block the car park but he was told to remove the obstructions by the emergency services as it could hamper access. Although technically trespassing, we are not breaking in or causing damage so nobody bothers us.