The aims of this study were (i) to investigate the participation in Triple Iron ultra-triathlons covering 11.4 km swimming, 540 km cycling, and 126.6 km running between 1988 and 2011 and (ii) to analyze the nationalities of the athletes achieving the fastest swimming, cycling, running and overall race times. Six out of seven races worldwide were held in Europe. Participation of male Triple Iron ultra-triathlons increased over the 24-year period while the participation of females remained stable at ~8% of the total field. Out of the 1,258 participants, 1.077 athletes (85.6%) originated from Europe. The number of male European athletes (r2 = 0.23; P = 0.02) and male North American athletes (r2 = 0.35; P < 0.01) increased across years. European males (2.161 ± 168.5 min) were faster (P < 0.05) than both European females (2.615 ± 327.2 min) and North American males (2.850 ± 370.6 min). Male European athletes improved (r2 = 0.18; P = 0.043), while European females impaired (r2 = 0.48; P = 0.001) overall race time. To summarize, participation in Triple Iron ultra-triathlon increased across years where most of the participants originated from Europe. European males achieved the fastest overall race times and improved their performance across years. Future studies need to investigate what motivates these athletes to compete in these races.