Celebrity Millennium is docked in Ketchikan, Alaska, after suffering mechanical issues on Sunday.

The ship was three days into its seven-night Alaska cruise, when it experienced difficulties with one of its two propulsion units, according to a Celebrity Cruises statement.

Although the vessel was capable of sailing without the affected equipment, the ship’s captain decided to have the matter investigated further.

“Upon further investigation, it is clear that our teams need additional time to fully determine the root cause of the problem,” the statement read.

In the meantime, the cruise line is compensating guests affected by the situation and will provide further details as they come to hand.