The woman, 39-year-old Kristy Manzanares, died aboard the Emerald Princess ship after a domestic dispute, according to a source with knowledge of the FBI's investigation. The agency is investigating the "suspicious" death.
Princess Cruises confirmed that the domestic dispute occurred at about 9 p.m. Tuesday and resulted in the woman's death.
Passengers were allowed to disembark at around 8:30 p.m. Wednesday after authorities lifted an hourslong lockdown, passengers told ABC News.
Passengers said the captain had previously instructed passengers in decks 8, 9 and 10 on the port side to return to their cabins so they could be interviewed by investigators about the incident. Other passengers were able to move about the ship, but not disembark.
One passenger had been detained by the crew, the cruise line said, adding that it has the authority to detain anyone who commits a crime.
The Emerald Princess was on a seven-day round trip cruise that departed Seattle on Sunday, according to the cruise line. The ship, carrying 3,400 passengers and 1,100 crew members, was scheduled to take a scenic tour around the Tracy Arm fjord near Juneau today, but that event has been canceled.
"Our thoughts and prayers are with the family and all those impacted by this tragic event," Princess Cruises said in a statement.
The FBI dispatched teams from Anchorage and Seattle to Juneau to talk to the family. The agency has jurisdiction in this case, it said, because the incident happened on the water.
ABC News' Alex Stone, Jennifer Watts and Karma Allen contributed to this report.