[Pseudoscience-is-malarkey (OP)]

People often think about the success of your Chunnel and the Hong Kong-Zhuhai-Macao Bridge when giving the situation a positive. But I think the English Channel's underwater tunnel China's HZMB are different beasts- Atlantic channel waters and deep sea Pacific waters have different widths, heights, temperatures, and currents. But, truth be told, the significance of these differences is lost on me.

[evan_au]

Comparing a Hawaiian link to the Dover-Calais "Chunnel":
Technical Feasibility
- The distance from Oahu to the next island (Kaua'i) is about 116km, which is longer than the 40km of sea crossed by the English-French Chunnel
- The water depth in the English Channel/La Manche is around 60m, with the Chunnel about 100m below sea level.
- The water depth between Oahu and Kaua'i is about 3.4 km, since these are the peaks of underwater volcanoes in the deep Pacific ocean.
- This depth of water makes drilling a Hawaii tunnel impossible, and erecting pillars for a bridge impractical (maybe a floating bridge, if people didn't get seasick, and they didn't have hurricanes...)

Economic Drivers
Two-Thirds of the population of Hawaii lives in Oahu: 1 million out of 1.4 million (2023 figures).
- The others have populations ranging from 200 thousand (the Big Island) to 70 thousand (Kaua'i).
- This is quite different economics from linking the population of UK (70 million) with Europe (700 million)

Cultural Desirability
One island of the Hawaiian group (Niihau) emphasizes retention of traditional Hawaiian culture, and this particular island does not welcome a flood of tourists or goods from the big city. They would not want a tunnel.
This is a stronger barrier than Brexit.

https://en.wikipedia.org/wiki/Channels_of_the_Hawaiian_Island