Stories and curiosities
Why Exceptional Pools Produce Exceptional Records: The Engineering Behind Fast Water
· 5 min read
In short
- Estimates suggest that wave drag can represent a significant share of the total resistance a swimmer must overcome during a race, although the exact proportion depends on speed, stroke and conditions.
- Several modern Olympic pools, including those used since the 2008 Beijing Games, are around 3 metres deep. This reduces the bottom’s effect on water flow and surface waves, although it is not a universal standard: the pool at the Paris 2024 Games was only 2.15 metres deep, prompting debate about its speed.
- Gutters around the pool’s edges absorb waves that would otherwise reflect back towards the centre and interfere with other swimmers.
- Lane ropes are specifically designed to dampen waves and prevent them from spreading from one lane into the next.
When record after record falls at a major competition, some of the credit belongs to the pool itself—it is not only about having faster swimmers.
Waves create drag
Wave drag can account for 5% to 12% of the total resistance a swimmer must overcome. The fewer waves that form and the faster they dissipate, the less energy the swimmer loses fighting their own wake and the waves created by others.
A depth of 3 metres
Several modern Olympic pools, including those used since the 2008 Beijing Games, are around 3 metres deep, although this is not a universal rule—the pool at the Paris 2024 Games was only 2.15 metres deep. Greater depth limits the bottom’s effect on water flow and surface waves, which would otherwise intensify the wave action in the pool.
Gutters and lane ropes
Waves reaching the edge of the pool flow into the gutters instead of reflecting back towards the centre and interfering with other swimmers. Lane ropes have their own wave-dampening design, greatly reducing the movement of waves between adjacent lanes. Together, these three elements—depth, gutters and lane ropes—create what swimmers call a “fast pool.”
The connection with timekeeping
Precise measurement is meaningful only when the environment is consistent. Pool engineering is therefore just as important as the touchpads that stop the clock. Read more in Swimming: touchpads and thousandths of a second.
The key takeaway
The same principle applies beyond swimming: conditions influence the result just as much as the measurement itself. In running and cycling, those conditions include the surface, gradient and weather. The timing system may measure precisely, but the final time always reflects the environment in which it was achieved.
Frequently asked questions
Why are swimming times faster in some pools?
It is due to a combination of pool depth, wave-absorbing perimeter gutters and anti-wave lane ropes. Together, they reduce wave drag, which estimates suggest can make up a significant share of a swimmer’s total resistance—from single-digit percentages to the low teens, depending on the conditions.
Why are some Olympic swimming pools around 3 metres deep?
Greater depth reduces the bottom’s effect on water flow and surface waves, causing less disruption to swimmers. It is not a universal rule, however: the pool at the Paris 2024 Games was only 2.15 metres deep, prompting debate over whether it was slower.
What purpose do the gutters around a swimming pool serve?
Waves reaching the edge of the pool flow into the gutters instead of reflecting back towards the centre and interfering with other swimmers.
How do anti-wave lane ropes work?
Their specialized design dampens waves and greatly limits their movement from one lane into the next, so waves created by one swimmer have less effect on competitors in adjacent lanes.