The Diving Universe

A Science Fiction series by American author Kristine Kathryn Rusch.

The Diving Universe includes three novels: Diving into the Wreck, City of Ruins, and Boneyards; and several additional short stories: The Spires of Denon, Becoming One with the Ghosts, and Becalmed.

Tropes used in The Diving Universe include:

• Absent Aliens: All known planets are colonized by humans. This was true even in the Fleet's time, 5,000 years before the start of the series.
• Anachronic Order: Squishy's chapters in Boneyards
• Bad Dreams: Boss is haunted by them. The most powerful involve her mother's loss to the Room of Lost Souls when she was seven, but others involve members of her crews who have died. Wreck diving is a dangerous business.
• Bi the Way: Squishy
• Black Box: Stealth tech. Not even the Fleet truly understood it; while they could create working anacapa from blueprints, they didn't actually understand how or why the anacapa worked.
• Celibate Heroine: Boss doesn't appear to have much in the way of romantic or sexual urges, possibly because of her dislike of company.
• Cloaking Device: Partial ones are available at the tech level of the current civilizations, but complete cloaking technology was available in the past. The Empire is attempting to recreate it at huge expense of money, materiel and personnel, and in the face of heavy losses to experiments gone wrong.
• Derelict Graveyard: The Boneyard in Boneyards
• The Empire: The Enterran Empire
• Everyone Calls Her Barkeep: The protagonist and main viewpoint character never gives nor uses her given name. She is only known as Boss. She explains this as motivated by not wishing any connection to the father who named her nor the family she detests.
• Faster-Than-Light Travel
• Fish Out of Temporal Water: The Ivoire
• Hyperspace Is a Scary Place: Regular FTL is perfectly safe, but then there's Foldspace. The Fleet tried not to enter Foldspace except in the case of an emergency, because not every ship that goes in comes back out -- and even if they do, there's no guarantee that they'll be in the right place or time.
• Lost Technology: Stealth tech. Boss wryly comments that, considering the circumstances, they should start calling it "Found Technology".
• Low Culture, High Tech: Any modern human attempting to use the vastly advanced stealth tech of the Fleet precursors falls into this. Not only do they mistake catastrophic malfunctions caused by the anacapa devices being 5,000 years older than their intended lifespan as a normal function of the technology, but they complete misunderstand what the anacapa was intended to be used for in the first place.
• Nanomachines: The Fleet's "nanobits"; now a Lost Technology that no-one even remembers, being mistaken for a strange natural phenomenon whenever they are seen.
• Never Found the Body: Most people killed by stealth tech don't leave behind bodies, which leads many to hold false hope that they are only missing and might someday be rescued.
• Older Is Better: The crew of the Ivoire are shocked that technology 5,000 years in their future is inferior to what the Fleet had.
• Parental Abandonment: Boss was dumped with relatives by her father after her mother died.
• Precursors: The Fleet, an armada of Dignity Vessels launched from Earth that traversed known space 5,000 years ago, using their superior technology to do good deeds wherever they went. Derelict Dignity Vessels are the source of the most valuable -- and most dangerous -- technology in the known Universe.
• Self-Destruct Mechanism: All Sector Bases have them, to prevent the anacapa from falling into enemy hands.
• Space Is an Ocean: Boss and her fellow "divers" are present-day shipwreck divers IN SPACE!
• Space Opera: of the grittier modern sort, but the expansive universe, far-future setting, available Faster-Than-Light Travel and general handwaving of technology place it firmly here.
• Space Pirates: Mentioned as existing.
• Standard Sci-Fi Fleet: We run into quite a few of these.
• Stealth in Space: Lots of ships have "cloaks" designed to hide them from detection, but none of them really work all that well. Hence the great interest in the Lost Technology "stealth tech", which according to legend could hide Dignity Vessels from any and all forms of detection.
• Time Is Dangerous: Stealth tech creates bubbles of altered time, which are usually fatal to anyone unfortunate enough to stumble into them.
• Used Future: Boss's profession and obsession is finding and exploring old wrecked spacecraft, and there are a lot of them about, with a history in excess of 5,000 years of space colonization.
• Year Inside, Hour Outside: Appears to be a common effect of remaining stealth fields.