Groton — Historic Ship Nautilus (SSN 571), the world's first nuclear powered submarine, and the Submarine Force Library and Museum, the Navy's official submarine museum, will close for semi-annual maintenance starting April 13.

The museum is scheduled to re-open on April 18, before closing once more until April 23. The submarine and museum are scheduled to re-open April 27, and potentially earlier than that if all planned maintenance is completed ahead of schedule.

After the semi-annual maintenance period, the museum and submarine will continue to observe winter operating hours, which are 9 a.m. to 4 p.m. Wednesday through Monday, until May 1.

On May 1, the submarine and the museum will shift to the extended summer operating hours, which are 9 a.m. to 5 p.m. Wednesday through Monday.

The museum and submarine are closed on all Tuesdays.

Admission to Historic Ship Nautilus and the Submarine Force Library and Museum are free to the public. For more information, visit www.ussnautilus.org.