Walrus is a tool for interactively visualizing large directed graphs in three-dimensional space, and is best suited to visualize moderately sized graphs that are nearly trees. By employing a fisheye-like distortion, it provides a display that simultaneously shows local detail and the global context. At any moment, the amount of magnification, and thus the level of visible detail, varies across the display. This allows the user to examine the fine details of a small area while always having a view of the whole graph available as a frame of reference. Graphs are rendered inside a sphere that contains the Euclidean projection of 3-D hyperbolic space. Points within the sphere are magnified according to their radial distance from the center. Objects near the center are magnified, while those near the boundary are shrunk, thus allowing the user to examine every part of the graph in detail.