History and Purpose
When Dexter bought the boat in the early 90s, he renamed it from Slice of Heaven to Slice of Life. The name is a pun. "Slice" refers to Dexter's use of blades. Up to this point, Dexter usually dumped his victims’ bodies in the Everglades. Looking for a better way of disposal, Dexter purchased the boat from Dr. Greenstein, Gene Marshall's psychiatrist, so that he could dump Gene's remains at sea. Dexter’s original marina, Coral Cove, was the same one where Harry had a slip.
Benefits and RisksIn Season Two, Dexter is almost revealed as The Bay Harbor Butcher when he wipes his boat clean in front of recently installed security cameras. But, before the footage is seen, he's able to hastily delete the files from Lundy's computer ("Dex, Lies and Videotape"). Later, he faces a worse crisis when Sergeant James Doakes attaches a GPS Tracking Device onto his boat and follows him to a kill site, where he confronts Dexter and discovers his secret ("Resistance is Futile"). It doesn't end well for Doakes, though, when Dexter captures him and keeps him locked in a cage.
Dexter also uses the boat to help him connect with others, such as successfully getting back on Rita's good terms by taking her and the kids on a fishing trip ("Left Turn Ahead"). He also goes fishing with Miguel Prado and, another time, takes Debra, Rita, and the kids on a trip.
In Season Seven, Maria LaGuerta discovers a discarded blood slide in the scorched church where Travis Marshall was killed, and compares it to the slides taken by The Bay Harbor Butcher. She sees the similarities between the two, and determines to clear James Doakes' name as The Bay Harbor Butcher. Soon, Dexter becomes her prime suspect, especially when she notices his name on a list of boat owners that used the Coral Cove Marina - the same marina as The Butcher. In "Argentina," Maria LaGuerta makes inquiries at the Coral Cove Marina. The dockmaster informs her that Dexter Morgan used to rent a slip there but he moved his boat in May 2007, even though he had eight months left on his lease. Later, LaGuerta suspects that Dexter committed another murder and she arrests him. However, Dexter had previously planted evidence on his boat to make it look as if she's framing him, so he is quickly released.
Louis Greene makes an attempt to sink the Slice of Life. However, Isaak Sirko comes across Louis and shoots him in the head, causing Louis to die on Dexter's boat. George is then ordered by Isaak to clean up the mess and get rid of Louis' body. When Dexter discovers blood on his boat while cleaning it, he tests it and surmises that Louis is dead.
Slice of Life's Fate
When Dexter and Hannah McKay decide to move to Argentina, Dexter makes an unsuccessful attempt to sell his boat. However, due to some delays (e.g. going after Oliver Saxon), Dexter ends up using the boat one last time to bury his sister at sea after he turns off her life support.
Upon realizing that he needs to live a distant life, in order to protect those he cares about, Dexter drives the Slice of Life toward Hurricane Laura. The boat is obliterated and, after the storm clears out, its wreckage is found about a mile offshore, with no apparent survivors.
In reality, Dexter was able to use its emergency life raft  to escape death from the Cat 1 hurricane, after which he moves to a remote, undisclosed location.
Dexter reveals a lot of information about the boat in "Monkey In a Box: when attempting to sell it off to a potential Boat Buyer:
She's a 2001 Century 2901 center console. I had this custom rail put in. New paint. Has a radar, GPS, fish-finder, autopilot, emergency life raft. And I had these twin Yamaha 250 four stroke motors put in. They got just over 400 hours, and when you open them up and you're out there...There's nothing like it.