A Kuiper belt
A Kuiper belt was a collection of planetoids found in the outer regions of a star system. In contrast to rocky asteroid belts, Kuiper belts tended to contain objects made of ice.
In 2375, Odo and the sixth clone of Weyoun attempted to evade pursuing Jem'Hadar attack ships by hiding in a Kuiper belt, taking their runabout, the USS Rio Grande, into the interior of a large chunk of ice and powering down. The Jem'Hadar forced them out of hiding by destroying every large ice chunk in range. (DS9: "Treachery, Faith and the Great River")