Zanzibar:

Scarce. Burton's long-lost, vast manuscript on Zanzibar, reappeared many years after its writing, affording Burton the opportunity of reliving his old Nile failure, and also the chance to write a serious appraisal of Speke's character and death. Beneath Zanzibar's exotic exterior, Burton found a state of near anarchy, disease, squalor, and a shamelessly open slave trade.