Oceans were long thought to exist in all corners of the Solar System, from carbonated seas percolating beneath the clouds of Venus to features on the Moon's surface given names such as "the Bay of Rainbows" and the "Ocean of Storms." With the advent of modern telescopes and spacecraft exploration these ancient concepts of planetary seas have, for the most part, evaporated. But they have been replaced by the reality of something even more exotic. For example, although it is still uncertain whether Mars ever had actual oceans, it now seems that a web of waterways did indeed at one time spread across its surface. The "water" in many places in our Solar System is a poisoned brew mixed with ammonia or methane. Even that found on Jupiter's watery satellite Europa is believed similar to battery acid. Beyond the Galilean satellites may lie even more "alien oceans." Saturn's planet-sized moon Titan seems to be subject to methane or ethane rainfall. This creates methane pools that, in turn, become vast lakes and, perhaps, seasonal oceans. Titan has other seas in a sense, as large shifting areas of sand covering vast plains have been discovered. Mars also has these sand seas, and Venus may as well, along with oceans of frozen lava. Do super-chilled concoctions of ammonia, liquid nitrogen, and water percolate beneath the surfaces of Enceladus and Triton? For now we can only guess at the possibilities. 'Alien Seas' serves up part history, part current research, and part theory as it offers a rich buffet of "seas" on other worlds. It is organized by location and by the material of which various oceans consist, with guest authors penning specific chapters. Each chapter features new original art depicting alien seas, as well as the latest ground-based and spacecraft images. Original diagrams presents details of planetary oceans and related processes.