While core-orientation data are becoming more and more necessary for marine sedimentological studies, there are no rugged, inexpensive, or convenient compasses that are insensitive to the ambient pressure, the inclination of the corer, and the bottom impact. This paper describes some instruments designed in an attempt to overcome these problems. A hemispherical compass, a free-floating spherical compass, an inexpensive "compass smasher," and some proposed simplified models of these are described....