Tripods installed with various instruments, data loggers, and a recovery system, are selfcontained, fully submerged structures that can rest stably on the seafloor. These bottom measurement systems can be used for nearly nondisturbed and longterm investigations on the seafloor. In the past four decades, tripods have made significant contributions to our understanding of the ocean chemical, physical, biological and geological processes. Some discoveries in deepsea observation have also been made from tripod experiments. The paper reviews the concept, development history, and applications of tripods.