Amsterdammers who spot a huge army-green submarine on a floating platform need not worry: it is the Walrus, a Dutch navy boat brought to the city to be scrapped.
The vessel, almost 70 metres long, arrived on the evening of Monday 12 October after thirty years of service.
The Ministry of Defence will not say where in Amsterdam it arrived, for security reasons.
Towed from Den Helder
It set off from Den Helder earlier that day, lying on a floating pontoon that special tugboats guided along the North Sea Canal.
In Amsterdam it will be taken apart, cut up, recycled and partly melted down.
The Walrus was built in Rotterdam and joined the navy in 1992, able to carry enough supplies and fuel to operate far from home for long stretches.
It was formally taken out of service three years ago, and Defence says the navy had used it up completely.
Replacements built in France
The submarines Dolfijn, Zeeleeuw and Bruinvis also need replacing.
Their successors, costing billions, are being built in France because Dutch industry can no longer build such boats itself.
NATO wants the Netherlands to remain strong underwater, since few countries have a submarine service.