[nuccy]

The extra distance for NY/NJ-Bristol cables to cover is "just" ~400-500km (extra ~7%), plus if you look at ocean floor map [1] it seems they prefer not to put the cable in the relatively shallow waters of Newfoundland or Nova Scotia (maybe this decreases possibility of a damage by anchors, or they compensate a bit in length by going deeper, i.e. shorter circumference due to smaller radius).

The other possibility is that the direct path passes underwater mountainous region with quite variable depths in mid-Atlantic [1], so going up-down or follow the valleys anyway would increase the cable length. The right answer is likely a combination of all these to minimize cable cost, maintenance and latency.

[1] https://earth.google.com/web/@41.47661069,-40.80459324,-4414...

[iptrans]

Ships anchors and trawlers are major risks for subsea cables. Deeper is thus better.

Underwater geography is also a major consideration. It's not just the going up and down, it's the risk of landslides, tectonic shifts, volcanoes, currents and icebergs scraping the ocean floor.

On top of that are geopolitics and enviromental concerns.

[nuccy]

1901 telegraph submarine cables [1] were more straight for a similar route. Likely because it was essential to make them as short as possible going underwater, so most of them were going from Ireland to Newfoundland.

[1] https://upload.wikimedia.org/wikipedia/commons/a/a5/1901_Eas...