SortStack #8 — 2026-06-17

By speed · Order from slowest to fastest.

1. A slowly marching sand dune 20161.8 mm/year

   Wind pushes desert dunes forward grain by grain, swallowing roads and even villages over the decades.

2. A duck paddling on water 1.6 km/h

   Ducks have no nerves or blood vessels in their feet, so they can paddle in icy water without feeling the cold.

3. A king penguin waddling on land 2.8 km/h

   A penguin's waddle is surprisingly efficient, storing and releasing energy with each side-to-side rock.

4. A domestic cat at full sprint 49 km/h

   A house cat can outsprint many dogs over short distances, but tires quickly after the burst.

5. A golf ball off the driver 340 km/h

   A driven golf ball can briefly spin thousands of times a minute, which is what makes it climb and hold the air.

6. A peregrine falcon in a dive 410 km/h

   The peregrine is the fastest animal on Earth, diving so fast it has baffles in its nostrils to breathe.

← All puzzles · Play today’s SortStack