4 stars; 5 stars for ambition, 3 stars for execution; the seas of the world (except the Mediterranean, the subject of a separate book by the same author) function mainly as a vista onto human activity; exploration, trade, travels, wars, described in a historical context. The scope is literally boundless and this is both its appeal and makes for an exasperating, exhaustive read at over a 1000 pages (or an audible listen clocking in at a solid 41 hours); worthwhile but you have to have the ‘Sitzfleisch’ to get to the end.