BOSTON—Undersea explorers say the wreckage of the Andrea Doria off Nantucket appears more badly deteriorated than previous sonar images suggested.

The Washington-based OceanGate submarine crew spent two full days at the wreck this month capturing more than a dozen sonar images.

OceanGate CEO Stockton Rush said Monday that the images suggest the entire bow has broken off since the last sonar images were captured two years ago by another organization.

Bad weather cut the five-person team’s expedition short, but Rush says the team plans to return next year to continue its sonar mapping project.

The Italian ocean liner went down in 1956 after colliding with another ship, killing 51 people. It’s since become a popular but dangerous diving spot that’s claimed the lives of 16 divers.