On April 20, a Waymo robotaxi traveling a 40-mile-per-hour road in San Antonio, Texas, encountered standing water across the lane ahead. A human driver would have braked, reversed, or found another route. The vehicle did none of those things. It slowed, then continued forward — into a flooded section of roadway that was, in the company’s own words, “untraversable.” The car was swept into Salado Creek. Nobody was aboard. Nobody was hurt. But days passed before the vehicle was recovered from the water. Three weeks later, Alphabet’s autonomous driving unit recalled its entire U.S. fleet. The voluntary recall, disclosed Tuesday through documents posted to the National Highway Traffic Safety Administration’s website, covers 3,791 Waymo vehicles equipped with the company’s fifth- and sixth-generation automated driving systems. It is the third recall Waymo has filed since February 2024, and by far the most consequential — both for its scale and for the uncomfortable question it forces into the open: when a self-driving car faces a situation no one fully anticipated, what happens? In this case, it drove into a creek. A Fleet That Grew Faster Than Anyone Knew The recall did something the company had not done voluntarily: it told the world exactly how many cars Waymo is operating. Federal recall filings require a precise accounting of affected vehicles, and the figure — 3,791 — surprised even close observers of the autonomous vehicle industry. Prior estimates, drawn from city-level permitting data, had suggested Waymo was running roughly 800 to 1,000 vehicles in San Francisco and around 500 in Phoenix. The company itself did not publicly acknowledge crossing the 2,000-vehicle threshold until September 2025. The recall number confirms that the fleet has since nearly doubled, making Waymo’s the largest commercial autonomous ride-hailing operation in the world. That growth reflects enormous capital behind the