Pérez-Reverte's stories of his trademark tired heroes aim to be adventure tales with canonical presentation, plot and denouément, and at the same time heavy in characterisation effort, with detailed descriptions of what goes through the mind of the leading character before he acts next. Typically, a book needs to be found, or a map, or a painting, or a crime needs to be solved, and there we go, following our grizzled hero in the adventure.
Basque director Imanol Uribe was attracted precisely to this type of classic adventure yarn when reading the novel: a sailor anxious to get back on a ship after a forced spell on land because of a legal problem finds the chance to do it, with a twist: there's a map (the nautical chart of the title), a beautiful and determined woman, a discovery to be made and a couple of bad guys. Obviously he reacts like 'gimme a break, this type of thing just doesn't happen any more...', but of course, there wouldn't be a story if that was the whole story. Classic Saturday-in-November, rain-outside, after-lunch-film fare.
And that's all there is, as far as the film is concerned. The characters then go from A to B to C etc, as the discoveries in the script dictate, but at the end of it all, the result is not terribly interesting. For starters, the aim of the search is nothing Earth-shattering, like the Holy Grail or the Ark of the Alliance, and to continue, the glue that holds the tale together, which is the obsession of Coy, the sailor, with Tánger, the woman, is largely lost and diluted.
One of the main criticisms made about this film is that it is dragged down by the use of voice-over (a resource which, if well used, produces marvellous results -witness Martin Scorsese's 'Casino' or 'Goodfellas', for example-, but if not well handled becomes a burden on the picture). Its use was an attempt to include that other driving theme of the novel, (apart from the voyage-and-discovery element), which is the age-old motif of the sailor tempted by the voice of a siren, a woman wiser than him who becomes to the mariner 'all women who ever lived'. Pérez-Reverte is a keen sailor himself, frequently going solo on his sailboat along the Mediterranean sea by whose shores he, and his character, Coy, were born. So, the sea, 'old and wise', the women who live by it, also growing wise after frequently waiting for their men gone to war since the times of the Odyssey, and the sailor who is brave when faced with danger and battle but often lost and rudderless in dealing with women, all form a part of the same canvas in which the story is set. Of course, this is quite interesting when read, but difficult to work into a basic film of X marks the spot, in particular when the original story tends to be a slow-burner to start with.
Carmelo Gómez is quite good as Coy the sailor, but Aitana Sánchez-Gijón had a tall order to serve, playing a woman who, without being extremely beautiful, toys with men more or less as she wishes. You do need to believe she's one to be able to pull that off for the script to work. The rest of the very short cast (pilot and two bad guys) are adequate.