Instead of crashing into the water 10 meters below, the front carriage ended up suspended dramatically in the air, propped up only by the silver cetacean.

The driver of the train, which had no passengers on board, was unharmed in the fluke incident which happened just after midnight at Spijkenisse, near the port city of Rotterdam.

In a twist of fate, the fortuitously positioned artwork is called "Saved by the Whale's Tail".

"This is such a weird scenario," Carly Gorter of the Rijnmond regional safety authority told AFP.

"The metro went off the rails and it landed on a monument called Saved by the Whale's Tail. So that literally happened.

"Because of the whale's tail the driver actually was saved, it's incredible."

The driver was later held for questioning, the safety authority said. The cause of the crash was still being investigated.

"The driver is going to the police station to ask him about his story. So this is normal procedure for these kind of accidents," said Gorter.

The sculpture was built in a park underneath the raised metro, its name a deliberate play on the fact that it is a "tail track" at the end of the line after De Akkers metro station.

It features two large whale tails poking out of the water, one of which saved the train.

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'Don't think he would have survived'

The architect who designed it, Maarten Struijs, said he was impressed that it could bear the weight of the train -- and that the driver was lucky he did not collide with the other, higher whale tail.

"If this tail was not so strong, not so low, then the driver of the metro train would have jumped 10 meters down and then I don't think he would have survived," Struijs told AFP.

"If he had bumped on the other tail then I think it would have been a different accident."

Struijs said the statue was not designed as a safety feature. 

"It was not made to save the metro, because it's more for the neighborhood and the people wanted to have something for themselves. So we made these two tails of the whale... for them, as a monument."

Stunned local residents turned out in force to see the bizarre sight -- so much so that local authorities urged them to stay away and to observe coronavirus social distancing measures.

A team of emergency services and experts, including the architect, was now on site to work out how to safely remove the train.

"The problem is it's water around it, so a crane isn't able to get there," said Gorter.

"How long this will take, we actually don't really know at this moment. I'm not guessing today so maybe it will still be there tomorrow," she added.

"We have a lot of wind at the moment and that's one of the issues that we're facing, that's a risk and worry."

In the meantime, Struijs said the metro train suspended in mid-air was a kind of work of art in itself.

"I could never have imagined it that way," he told Dutch public broadcaster NOS.