...because foreign overseas trade routes are terrible.Whales are sometimes useful in isolation, since you probably will be beelining optics, but, at the same time, if you built Colossus, which is often good in isolation, you may not be beelining Astronomy... so it can be a while from there to Combustion.
...because foreign overseas trade routes are terrible.
Colossus is a joke compared to them.
Trafalgar Square Wonder that is a combination late-game Colossus and Naval HE, that also grants additional xp to naval units; very potent on water maps, and half-price with Whale.
But it's sometimes reasonable to pick up whales with a second border pop...