That BBC documentary shows or exposes very shallow thinking skills at this timestamp 6m42s:
https://youtu.be/_xZCh8eDZFc?si=AHyDPgoDucsCRllS&t=402
They claim the panama canal is continuously fed by freshwater for the canal locks (which segment the canal into sections with different water levels, and which enable ships to be raised or lowered to the next water level during travel along the canal).
It's 2026, why are humans dumping freshwater into the oceans? This can perfectly be done without wasting freshwater.
Archimedes screws can essentially be operated quasistatically at extremely high efficiencies. The energy released when lowering can be stored either in gravitational energy of a mass, or be used to power a second parallel lock operated in counter phase (so while one lock is lowering ships say eastwards, the energy is used to raise ships traveling westwards, and afterwards their roles reverse). To speed up a second gravitational potential energy store (and optional flywheel) can be used to accelerate and decelerate the pumping. Apart from some frictional losses (minimal compared to the potential energies involved) this doesn't cost energy, and is easily covered by a small number of solar panels.
Is this misreporting by the BBC, or is it mismanagement by the Panama Canal operators?
Keep the freshwater, use it for irrigation etc, make Central America more attractive to South American refugees and the migration burden on Mexico and US lowers.
The operation as currently described is so inefficient, even for the 1960's!