Several new devices that demonstrate a variety of known phenomena in fluid dynamics are presented. These add on to a recent collection of demonstrations and follow the same design features as documented earlier (self-contained, easy to use, low cost). Descriptions are provided to enable replication by others, using readily available materials. The significance of each demonstration is outlined and background information on the relevant physics can be found in the cited references. The devices can be generally used in classroom lecture demonstrations, outreach activities, or other student-based projects. However, pedagogical details are left to readers' discretion, depending on the scope of local interests and constraints. Video samples of demonstrations are available online. [For "Fluids Demonstrations II: Bubbles in Mondrian Painting, Eruption-Like Flow, Rotational Instability, and Wake Vortices," see EJ1236399.]