The Hanso family are selling this ledger because they are trying to raise money to gain funding for the Hanso Foundation which they lost in 1980.
The diary charts down the course the Black Rock sailed on, and thus explains how to get to the Island.
The Hanso family, which is said to have owned the diary, used this information to start the DHARMA Initiative.
Widmore wanted the diary because he knew both that the Hanso family was involved in some project on the Island (and he wanted to find it) and that the Black Rock wreckage had never been found. As the journal contains coordinates logged by the Black Rock crew, he believed that the journal could lead him to the Black Rock, and thus to the Island.
He spent his fortune looking for the secret cargo of the Black Rock. Years later he sent the freighters.
Other groups wanted the diary because they also wanted to know how to get to the Island.
The boat was sent by one of the other groups.
Widmore used the diary to plan his race around the world.
Widmore's annual yacht race would be a great cover to try an explore and search for the Island. I mean, that's how Desmond got there.
There is an unidentified, anonymous bidder ("the caller") at the action who seemingly bids against the rest, Mr Widmore included.
The diary came into the possession of Alvar Hanso some time in the 1950's after he purchased the New World Sea Traders company from the East Ocean Trade Group, renaming it to the Allied Copenhagen Marine Merchants. The New World Sea Traders was the company owned by Alvar's great-grandfather, Magnus Hanso. This diary was in the records of the New World Sea Traders and described the Island and its powers. The dairy was evidently written by a crew member of the Black Rock, and he managed to leave the Island, possibly dying later from the effects of "time shifting". Alvar Hanso located the Island and set up the DHARMA project in order to use the Islands unique properties to aid him in research that was designed to save the world. In 1985, something happened to the project (see the blast door map) and later there was some sort of corporate "shake up" and Thomas Mittelwerk took over the project (see The Lost Experience). His intentions were not so altruistic, and his interest in the Island was for power, money and possible world domination. Mittelwerk involved Widmore Industries and a number of other companies (e.g Paik Heavy Industries) to put his plan in effect. Ben, having knowledge of the direction the DHARMA project had taken, instigated The Purge to shut down what remained of the DHARMA Project, which prevented Mittelwerk and his cronies from returning to the Island. The diary was purchased by Widmore in an effort to regain infomation needed to find the Island once more. Widmore may even be trying to divest his relationship with Mittelwerk, since In Chapter 39 of the book Bad Twin, board members of the Widmore Corporation describe fellow board-member Mittelwerk as "dangerous...ambitious and brilliantly two-faced, a man acting out an agenda all his own." Ben and the The Others know this history of the DHARMA project and these subsequent events, and they are the good guys, trying to prevent anyone from using the Island for evil purposes.
Widmore's animosity toward Desmond is about more than just "protecting" his daughter; he is related in some way to DHARMA and knew what role Desmond has to play in the grand scheme of things.
The ledger contains information relating to the location and properties of the Island. It is the only description of the Island and how to get there that ever made it back to the outside world. This information was used by Alvar Hanso to locate the Island and to place DHARMA Initiative personnel there, and now Charles Widmore, who covets the Island for himself, intends to buy the ledger to use it for the same purpose.
The Ledger was found in Madagascar because the Black Rock was in port in nearby Mozambique at some stage, probably to pick up the slaves it had onboard.
In the Season 1 episode "Exodus, Part 2" Locke said that the ship "must have been en route to a mining colony--(it) probably set off from the eastern coast of Africa--Mozambique". Madagascar and Mozambique are virtual neighbours.
That would also explain the dynamite in the ship's hull.
Not really - dynamite wasn't invented until 1866. - the ship sailed in 1845.
This suggests the Black Rock was grounded and they were stranded on the island for 7 years and then finally escaped the Island somehow and then made it to Madagascar.
Or the Ledger may have been lost or stolen when the Black Rock was in the Madagascar region before the ship disappeared.
The writers probably just picked Ile Sainte Marie because it was a notorious pirate haven back during that period of time. It likely indicates nothing about the Black Rock, its courses, or the location of the Island--it's just where the book happened to end up after five years of trading hands.
If the ledger was lost before the Black Rock ended up on the island, then it could still give clues as to the direction the ship was heading next. If the ledger was still with the Black Rock when the ship ended up on the island, then how did the ledger get off the island? Is it possible that the Black Rock found the island more than once, and that the ledger was lost before the ship ended up there for good?
Is it possible the pirates found the island and the ledger, then managed to leave?
The ship sailed for the last time in 1881, not 1845.
While purportedly lost at sea following its 1845 voyage to Siam, it's possible the master of the Black Rock decided to convert it to a mining/slave ship at this time and "vanished" from official trading records. The ledger could have been lost by legitimate means, or left behind to facilitate this deception. Either way, the public and other official sources now assumed the ship had sunk.
Subsequently, it engaged in (possibly illegal) mining practices in the New World using slave labor purchased from European jails. Its actual final voyage was in or after 1867 with Richard Alpert as one such slave.