<p>Helium-filled soap bubbles have emerged as state-of-the-art fluid flow tracers for large-scale volumetric measurements over the past 15&#xa0;years. Owing to their relatively large size, ranging from a few hundred microns to a few millimeters, they scatter significantly more incident light than conventional micron-sized fog particles. Although this enables orders-of-magnitude larger measurement volumes and reduced costs associated with illumination, they are also impacted by challenges associated with reliable and consistent generation, dispersion in particle response times, short bubble lifetimes and wind tunnel seeding methods. In this review, we discuss the parameters that govern the behavior of helium-filled soap bubbles in fluid flows and summarize the efforts to-date to quantify and validate their behavior. We highlight specific aspects that will play an important role in establishing their use in future experiments as well as avenues to tackle these challenges.</p>