Ship: Professor Molchanov, built in 1982, can hold many people.
Location: Barentsburg on the Svalbard islands, which belong to Norway.
Legal reason: To support a $4.22 billion compensation order for the Ukrainian company.
Russia says the seizure is like piracy and wants the ship back.
Norway says it will keep people safe and discuss ways for them to leave.
The ship is linked to a big money case between a Ukrainian energy company and Russia.
The case started because Russia took property in a place called Crimea many years ago.
Both sides say they are following the rules, but they are still arguing.
The crew and passengers are safe, and Norway is helping them travel home.
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