A bright, diffuse nebula, NGC 3373, surrounding the star η Carinae. About 2° across and divided by a dark, V-shaped, obscuring dust-lane, it contains a number of interesting stars and star clusters, and also two major included nebulae—the bright Homunculus Nebula and the dark, absorbing Keyhole Nebula. Its distance has been estimated as about 8000 light-years.