Scientists have built a scale model replica of Colwyn Bay seafront, hundreds of miles from the sea.
The 1-in-50 scale miniature was created to test planned improvements to the beach and sea defences.
Specialists HR Wallingford built it at the company's research centre in Oxfordshire.
Tom Rigden, of the firm, said: "Computer models are improving all the time, but there's still no substitute for a physical model."
Conwy council, which commissioned the model, wants to extend the sandy beach from the centre of Colwyn Bay around to Rhos-on-Sea.
However, it needs to test how much sand is needed and how long it will stay in place before the waves wash it away.
Benji Poulton, the council's project manager, said: "Bringing in the sand is a very expensive operation, so we need to be sure that when we did bring in the sand, it will stay in the area where we put it.
"Having a model built will test the theories for a fraction of the price and give us the chance to optimise our design before we go ahead."
In 2013, the council brought half a million tonnes of sand to the beach, close to Colwyn Bay town centre.
The results of this experiment will help it to do similar work with a new section of seafront and to improve the beach and the sea defences around to Rhos-on-Sea.
The model includes wave-making machines, a replica coastline and even a miniature version of Rhos-on-Sea breakwater and slipway.
Mr Rigden, of HR Wallingford, said: "It's a 1-in-50 scale model - that means one metre in our model is equivalent to 50 metres in the real world.
"The coast is extremely complicated. The physical processes with waves, sea bed and sea shore are complex, and the forces involved are immense.
"The best way to get an idea of what is happening is to build this scale model, which allows us to test all the forces, all the processes in one go."