Hergé did not write the 1972 film which was instead written by Greg (Michel Régnier), then the editor of Tintin magazine, whilst it was directed & produced by Raymond Leblanc, the publisher who had set up the magazine and rescued Hergé from his immediate post war problems before going on to set up Belvision Studios. Bob de Moor, one of the founders of the Studios Hergé who provided support and backgrounds, was the Graphic Consultant. Belvision Studios had produced the first series of cartoon adaptations of the Adventures, first for television and then for the big screen in the form of The Calculus Affair (a compilation of the television adaptation of the album of that name) and then Prisoners of the Sun (a straight to cinema to adaptation of both The Seven Crystal Balls and Prisoners of the Sun). Thus The Mystery of Shark Lake boasts the strongest credentials of any Tintin production that lacks the direct involvement of Hergé himself (though he had some supervisory role). With Hergé's stated desire that the Adventures would not continue after his death having been adhered to, this is thus the only non-Hergé Tintin story of any official standing. (Hergé is credited on the spine on some, though not all, editions of this album, but the title page is clear that it is fact based on his characters.)
The book appears to be using stills from the film itself as the basis for the pictures, though a comparison shows that at least some of the precise shots are absent from the finished picture and there are a few differences - for instance in the film, Captain Haddock uses a dead match to draw a moustache on the poster of Bianca Castafiore but in the book he uses a pen. Whatever the precise origins of the pictures they are clearly sourced from Belvision itself, to the point that the same highly detailed backgrounds are in use with the more simplistically drawn and coloured characters in the foreground, a consequence of the animation techniques of the era but one that produces images that don't always gel together too well. The regular characters are drawn in their familiar appearances, though it's notable that Tintin's wardrobe has been slightly updated and instead of his traditional plus fours he's now wearing standard length trousers. The art aims at the style of Hergé but is all too clearly not his own work. The script is again taken from the film, at times a little too much as there are many captions and even some panels composed entirely of words that provide narration which feels too much like stage directions. This affects the pacing of the book, with some key plot scenes flowing rather quickly, whilst the action scenes are more drawn out.
The plot itself feels fairly traditional, with Professor Calculus in the process of inventing a machine that can create identical duplicates of objects, though it is not yet perfected. This attracts the interest of a criminal masterminding the theft of priceless works of art and jewels, leaving forgeries behind. Unfortunately this is a plot hole as the story opens with the theft of a pearl with a brilliant forgery being left in its place, making it strange that so much effort has been gone to in order to capture the machine when the criminals are doing just as well without it. Worse still is the extravagant nature of the villain's base, located within the lake that Calculus happens to be working right beside. And bizarrely Calculus's work is deemed sufficiently important to have security (even if it is Thompson and Thomson), yet he's working right by a lake that forms part of the border between Syldavia and its rival Borduria. The lake itself is artificial, suggesting a bizarre level of co-operation between the two countries.
Presumably to provide child appeal, the story contains the extra characters of siblings Niko and Nouchka and their dog Gustav. In book form they're less annoying than on screen and there's naturally no irritating song to endure. But they still feel rather out of place in the story and too much attention is devoted to their independent escape and use of an underwater tank. Gustav is even more redundant, being just a cute animal to add to the scenes and does nothing that couldn't have been done by Snowy himself.
The film reflects a strong influence from the Bond movies with an over the top villain operating out of a hi-tech hidden base with fancy vehicles, secretly monitoring his targets through spies and hidden cameras. The villain uses the code name "King Shark" but is revealed to be Rastapopoulos. His appearance here is the one potential problem with continuity with the canonical Adventures as he's clearly survived with Tintin thinking him dead and he's imprisoned at the end of the story. There's no explanation for how he's escaped the aliens in Flight 714 to Sydney but it doesn't really work to set this adventure before then. Otherwise it would not clash with the regular series though there are other reasons for not including it in the canon. Rastapopoulos is at his most arch in this setting, yet he also appears far more honourable than before, being willing to release the children in exchange for Calculus's device and only reneging on this deal because the device is not as he was expecting. However his foolishness is also present when his attempts to escape by submarine through an underwater channel fail because he's left the periscope up.
This story has the traditional mix of intrigue, action and slapstick comedy of a Tintin adventure but it doesn't really mix well enough to feel like a genuine entry. Part of the problem comes from the excessive emphasis on the children and their dog who feel as though they've been stuck into the story by executive order. Calculus's device also feels more fantastic than is usual for the stories, as does Rastapopoulos's base. The look of the piece is jarring and the pacing off, at times feeling more like a condensed series of storyboards than anything else. Ultimately this is a flawed adaptation of a film that doesn't effectively capture the nature of The Adventures of Tintin and can be safely ignored.