Marine megafauna research has sometimes faced criticism from the marine science community for two contrasting reasons, the first possibly stemming from the second. The issue is that, with large, often rare, widespread, and difficult-to-manipulate animals, controlling study species is inherently limited (whales don’t fit in test tubes). This challenges hypothesis-driven experiments, so much of the research relies on descriptive or quasi-experimental methods. In earlier days, purists were unduly critical of these large-scale observations. The second reason is that marine megafauna are charismatic and have a high public profile. This has led to a mistaken belief that research in this area is oversubscribed and receives a disproportionate share of limited scientific funding. Having spent the last 40 years conducting research—from blue-sky studies (play, communication, reproductive, social behaviour), through strongly applied work (biologging and acoustic telemetry to understand both animal movement ecology and support long-term ocean observing crucial for climate change, weather forecasting, and operational oceanography), to crisis science (addressing the decline of critically endangered species)—I argue that marine megafauna science is robust, diverse, and highly cost-effective. I will illustrate with examples where we have made real-world impact, and also discuss areas where we have been less successful.