NAUTILUS is an ultracryogenic resonant-mass gravitational wave (GW) detector. It was installed at the INFN Frascati National Laboratories in 1992.

NAUTILUS is part of the international network of resonant-mass detectors which includes ALLEGRO at the Louisiana State University, Baton Rouge, AURIGA at the INFN Legnaro Laboratories, and EXPLORER at CERN.

After a period of continuous data taking from may 1998 to january 2002, NAUTILUS has undergone a complete overhaul of its read-out electronics (capacitive resonant transducer, superconducting transformer and dc SQUID).

NAUTILUS is now gathering data since june 2003.