Undersea WAN connections

I work in Texas and my company does tech support for a client based in Hawaii. Last night I was talking to a couple of the account managers and I asked them how we connect to their computers. They hadn’t really thought about it (?!?) but presumed it was a T1 like all our other clients. I was skeptical that a T1 could be laid across the Pacific Ocean, but this map shows that that is exactly the case. My question is how are these cables laid? Are they dropped into place? Secured by divers? From looking at the terrain on that map, it seems like it would be the equivalent of dropping cables on top of the Rocky Mountains. Securing them to the sea floor would involve complicated routes up and down mountains, through valleys, off cliffs, etc. How’s it done?

Wired magazine had a feature several years ago in which Neal Stephenson chronicled the laying of an undersea cable from UK to SE Asia. I haven’t read the online copy linked below, but the print article was excellent both in technical detail and because Stephenson is a joy to read.

Very interesting link…haven’t read the whole thing, but the cable laying process starts on page 17, and page 28 is where the actual placement is addressed:

If the bottom is hard, currents will chafe the cable against it - and currents and hard bottoms frequently go together because currents tend to scour sediments away from the rock. If the cable is laid with insufficient slack, it may become suspended between two ridges, and as the suspended part rocks back and forth, the ridges eventually wear through the insulation. Sand waves move across the bottom of the ocean like dunes across the desert; these can surface a cable, where it may be bruised by passing ships. Anchors are a perennial problem that gets much worse during typhoons, because an anchor that has dropped well away from a cable may be dragged across it as the ship is pushed around by the wind.

Sounds like ideally the cable rests on the sea floor, secured only by gravity, and that in some places the cable is close to the surface.
This is an interesting passage about undersea cables in history:

**In 1870, a new cable was laid between England and France, and Napoleon III used it to send a congratulatory message to Queen Victoria. Hours later, a French fisherman hauled the cable up into his boat, identified it as either the tail of a sea monster or a new species of gold-bearing seaweed, and cut off a chunk to take home. Thus was inaugurated an almost incredibly hostile relationship between the cable industry and fishermen. Almost anyone in the cable business will be glad, even eager, to tell you that since 1870 the intelligence and civic responsibility of fisherman have only degraded. Fishermen, for their part, tend to see everyone in the cable business as hard-hearted bluebloods out to screw the common man. **
Thanks for the link, micco!

Without reading the provided link, so apologies if it is answered on it.

How does it work with undersea trenches? Is the cable suspended “above” them or does it follow the floor, no matter how deep?

More stupid questions (without reading the article yet) - How did they bring the cables down the first place? It sounds really deep for divers and they have to struggle with those long cables. If they are optic cables then they have to be laid in one long stretch, doesn’t it? (Or so my lecturer once told me). If some freak accdient happens and part of the cable tore away, how do they pin-point it, and how soon can they fix it?