SCOTT BEVAN, PRESENTER: For maritime archaeologists it's a dream come true - a surprise find in a car park in the quiet WA coastal town of Bunbury.

Five metres below the surface the team has found historic hidden treasure and experts say there's no site quite like it in the world.

Nikki Wilson-Smith reports from Western Australia.

NIKKI WILSON-SMITH, REPORTER: This isn't what you'd expect to find in a coastal car park. In Bunbury Western Australia what was a haunt for hoons has become something much more significant - An archaeology dig.

ROSS ANDERSON, MARINE ARCHEOLOGIST, WA MUSEUM: We're just hitting solid material all through here and it's wooden so it's a pretty good sign that there's another shipwreck here.

NIKKI WILSON-SMITH: The area around Bunbury is known as the shipwreck coast and there have been rumours through the years of American whaling ships wrecked near the beach and smothered by sand.

John Cross was 16 years old when he worked at a sand mine at this site. In 1961 he was on night shift when he struck wood.

JOHN CROSS, EXCAVATOR: I hit this what seemed like something solid, it wasn't a rock and it wasn't steel, it just felt - seeing I have a process of working it turned out it was wood and it was Oregon wood and Oregon wood is American.

NIKKI WILSON-SMITH: John Cross thought he had hit a shipwreck but no-one was very interested in his find. Fifty years later he's back working on the same site as a member of an archaeological dig to confirm his suspicions that this car park is a shipwreck grave yard.

JOHN CROSS: Much fun, best job I've been on in my life actually. I've had some tough jobs in my time you know and this is about the best I've had. So I'm sort of whistling Dixie you know.

NIKKI WILSON-SMITH: And it turns out his hunch was right.

ROSS ANDERSON: This would have gone down is side of the hull so it's a piece of deck that's fallen over on its side.

NIKKI WILSON-SMITH: And you can see there there's still barnacles on that piece of metal.

ROSS ANDERSON: That's right, yeah, so we know this was in the inter tidal zone at one stage.

NIKKI WILSON-SMITH: Ross Anderson is the head marine archaeologist at the West Australian Museum and he's leading the excavation. He has been fascinated by the stories of American whaling ships wrecked at Bunbury and says there is no other site quite like this in the world.

ROSS ANDERSON: As a resource, so with three of them we think in the same location is absolutely unique. So it's that unique combination of circumstances where you get material and wrecks and everything and then it gets sealed up by modern development and coastline changes and that's resulted in just sealing this as almost like a shipwreck park.

NIKKI WILSON-SMITH: One of the ships found is a mystery and scientists are currently testing wood samples to try and work out what it is and while it's yet to be confirmed, archaeologists believe the other two ships on site are American whalers wrecked here in the 1800s.

ROSS ANDERSON: One of them, the Samuel Wright, which is the earliest one, is a Salem whaler. So the Salem whalers were the first ones that really came and explored these grounds in Western Australia and then everyone sort of followed them. So like the gold rush this was like a blubber rush.

NIKKI WILSON-SMITH: The second ship, the North America, was wrecked here in 1843 as the confused captain tried to outrun a comet. Now the ship's hull has been uncovered, preserved over time.

ROSS ANDERSON: We were hoping with the water probing to find wooden structure and ballast or something like that but to actually get an intact bow structure with all of that diagnostic information, it was quite, you know, that was a bit of a fluke. You know, we were looking in the right place but to actually come right down on that particular piece of structure was fantastic.

NIKKI WILSON-SMITH: It was also fantastic for Ray Parks, a Bunbury surveyor who estimated the location of the wrecks using historic maps.

RAY PARKS, SURVEYOR: That was 27 years ago so it's great to see that today they are where I thought they were, where I positioned them. It was quite traumatic, actually, waiting to see if something was going to come up and it did so you feel a bit justified. You feel your work was right.

NIKKI WILSON-SMITH: After years of planning, days of digging and hours recording painstaking details, the archaeologists conducting this dig will simply push the sand back over the wreck and leave it just as they found it.

VICKI RICHARDS, CONSERVATION SCIENTIST: If they're in good environmental sort of condition for preservation of the wreck then we suggest that it stays there, it gets covered up and hopefully it will be there in the future when there's more archaeological questions to be answered.

NIKKI WILSON-SMITH: But locals are disappointed.

RAY PARKS: In a sense you feel a sense of loss when they get buried again and you can just say well there are some wrecks under there because they are a very big part of Bunbury's heritage and I understand there's not too many American whalers that are still intact in this type around the world. They were mainly broken up.

NIKKI WILSON-SMITH: While the community waits to see what the future holds for the car park whalers, John Cross is happy to find the answer to his own 50 year old puzzle.

JOHN CROSS: There's probably half a dozen in here so we've just got to wait and see. It's a shame they're going to have to cover it all up because they've achieved so much and now they're going to cover it up but I suppose good for someone else to come along in 50 years and have another dig, you know.

SCOTT BEVAN: How hard will it be to push that sand back over the site. Fascinating stuff, terrific story too by Nikki Wilson-Smith.