NO SPOILERS
I played through From Shore to Sea with my "caveman shaman" Gurkagh, and had a great time. It's a really atmospheric adventure with a strong story and lots of room for exploration and adventure in an open-ended way. Although the beginning is a little rough, on the whole the writing is really strong. However, the monsters in the module are also really strong! Probably a bit too strong (combined with other factors) for an average group of sixth level characters to successfully complete it. I'd definitely recommend groups play through the module, but maybe not until they're a level or two higher than what's stated on the cover.
SPOILERS
From Shore to Sea takes place in two locations in the Hellmouth Gulf, which is a remote and rarely-visited area off the coast of Cheliax. The first location is the village of Blackcove, where the PCs quickly get the sense that something strange is going on, and the second location (where the bulk of the gameplay is set) is a small island off the coast called Nal-Kashel. The gist of the adventure is the PCs exploring Nal-Kashel and piecing together clues to realise that an aboleth (trapped underground since the days of Old Azlant) has been mind-controlling villagers from Blackcove to help it escape! The adventure background is pretty complicated (and perhaps over-complicated for a 32-page module), involving Nal-Kashel (an ancient Azlanti observatory and university); the villagers of Blackcove who, for generations, have been birthing gillmen; a strange curse on the island; off-shore colonies of skum; an alchemist named Gerlach who tried and failed to solve the mystery of Nal-Kashel; and the aforementioned aboleth with the fitting name of Mohlomog. I won't go into all of the backstory here, though bits and pieces will come out later in the review.
Part One ("The Shores of Hellmouth Gulf") starts off with the PCs walking along the coast of the Hellmouth Gulf. Absolutely no mention whatsoever is given for why the PCs might be doing this, so a GM is going to have to make up a reason from scratch. I like it when modules give at least a small sidebar listing possibilities, because if the initial adventure hook doesn't sink in, it can be hard for the GM to get things on track. The adventure hook for this module is pretty weak, I think. The PCs hear a scream in the distance and see a man in an old rowboat fighting off an attack by giant crabs. If a rescue is made in time, the man will explain that his wife is from the village of Blackcove up ahead. The couple followed a local tradition and went to spend the night on an island (Nal-Kashel), but she was abducted by strange sea creatures and the man barely escaped. He asks the PCs to travel to Blackcove and the island to see if they can rescue her, and says there's lot of ancient golden artifacts in the area. The reason it's a weak adventure hook is that Blackcove is five hours out of the way down a rarely-used road, the husband is too scared to accompany the PCs (instead, he flees back to his own village, which isn't a trait likely to make PCs feel sympathetic towards him), and no provision is made for what the GM should do if the man is killed or rendered unconscious during the battle against the crabs. Fortunately, despite a poor start, the rest of the module gets better.
When the PCs reach Blackcove, they see a village that looks almost entirely abandoned. The village has a great, creepy vibe, and the module uses the most of little vignettes, weather effects, and description to help get a table in the right mood. This is a gray, misty, lugubrious place like something out of Lovecraft's Kingsport. Eventually, the PCs will encounter one of the few remaining villagers, and the group is (quite organically) steered toward visiting the lighthouse, where an assembly is taking place. PCs can start to gather some information about what's going on here (with a nicely written and detailed section on what different Diplomacy check results will reveal) and probably learn that a local man named Gerlach visited Nal-Kashel some weeks ago but never returned. There are fears that he must have "stirred something up," and, ever since, more and villagers have been disappearing. Many of the villagers are revealed to have fish-like traits (and are mechanically Gillmen), though this is a generations-long phenomena and not something directly tied to the current adventure.
A very cool and cinematic encounter takes place in the lighthouse. The waters of the bay begin surging and flooding lower levels, while a massive (off-screen) sea creature begins probing the higher levels with gigantic tentacles to batter and snatch villagers! The PCs have to try to simultaneously keep people from panicking while fending off the tentacles. The battle is handled in an abstract way (a grid isn't supposed to be used, and there's not a floor map of the lighthouse), and when I played through it there were parts that were somewhat cumbersome because so many PC abilities assume precise areas or distances that just weren't available. The encounter goes on until a certain number of tentacles have been destroyed or a certain number of villagers have been taken, and I don't think our group got the positive result! The PCs, as professional adventurers, are naturally asked to travel to Nal-Kashel and rescue the (presumably kidnapped) villagers. Some financial incentives are offered, and a local man is willing to ferry the group over in his boat. In a really nice twist, once the journey is underway, the man transforms rapidly into a skum (a croaking evil fish-man) and attempts to rock the boat and pitch the PCs into the sea! This is an encounter that could be pretty lethal for PCs who haven't taken the necessary precautions; though, if they're in a module called "From Shore to Sea" and don't have any ranks in Swim, I don't feel *too* bad for them.
Part Two ("The Ruined Island of Nal-Kashel") involves exploration of the island. One of the common criticism of RPG adventures is rail-roading, but one of the real strengths of From Shore to Sea is that it's very open-ended. There are several locations that be visited in any order, and they're really cool, fitting the theme of an ancient Azlanti scientific outpost quite well. There's an old archives, an observatory, some mysterious towers, an astronomical center, and more. Most of the locations hold encounters and, when combined with the random encounters listed on a chart, the PCs are likely to have a pretty tough time just surviving. There are chuuls, rust monsters, a giant octopus, some particularly nasty (recurring) traps, and more. A particularly difficult location is the observatory which turns out to be crucial for the PCs to understand and solve the mystery of the island but it pulses with constant damaging effects. At one of the locations, the PCs will find the missing villagers--but they've obviously been mind-controlled and forced to dig out a tunnel from the sea into the interior of the island. There's no realistic way to rescue them, as an unlimited number of skum intervene (in waves every few rounds) if the PCs try.
Adding to the difficulty is that when the PCs step foot on the island, they will, sooner or later, be affected by a mysterious curse that starts to gradually give them fish-like traits! At first the changes are innocuous or even mildly beneficial, but the problem continues to get worse the longer the PCs spend on the island--and this isn't a place that can be handled in a quick SWAT-team style sweep.
Another issue was what ended up leading the group I played with to decide to leave the island with the task unfinished: this is definitely an adventure for smart PCs with lots of skill in Spellcraft and Knowledge (arcana). The complex backstory makes it hard to tell which of the various problems are just part of the island's magic and what parts are related to Gerlach's visit, and the problems of the taint and the (tough!) random encounters make too much lingering and back-and-forth between locations (to experiment with different ideas) a dicey prospect. Depending on party composition, the necessary skills and problem solving abilities just might not be available, and, unfortunately, I don't think there's really a way around it here. I didn't mind too much, as I think different characters with different skillsets should get a chance to shine in different adventures. We just happened to have the wrong group of characters, and couldn't figure out how to move forward.
Part Three ("The Natatorium of Mohl'omog") details the subterranean caverns beneath the island. Here, the PCs will encounter Gerlach (a sorcerer who has been dominated by Mohl'omog), multiple traps and ambushes, and, finally, the aboleth itself. My group never made it this far, so I can only evaluate the section from reading it, but I'd be honestly surprised if a group of normal sixth-level PCs survive it. There are multiple CR 5-9 encounters in short order, and one bad saving throw vs. the aboleth's domination ability can result in PCs fighting each other.
It's ironic, from an internal story perspective, that things probably work out fine (at least in the short- to medium- term) if the PCs never visit the island. Once the mind-controlled villagers dig the aboleth free, it swims away to carry on centuries-long evil machinations and schemes, and likely leaves Blackcove alone. I'm not saying aboleths on the loose are a good thing, but Mohl'omog has been out of currency for a while, and it's not like he's the only aboleth in the big blue sea. I suppose that's neither here nor there, however.
We can't move on without recognising that awesome cover--definitely poster worthy! The inside front cover is a map of the island of Nal-Kashel,while the inside back cover is a map of the observatory. The maps are done in an interesting and unusual style that I don't really know how to describe. For the sake of completeness, I'll mention that there's a page containing capsule stats for four level 6 Iconics; Paizo stopped doing this in the module line after a while, but I think there is something to be said for being able to get a game up-and-running quickly even if not everyone has original characters (though, I'm sceptical the foursome would be tough enough to survive the island).
Overall, I love the feel of From Shore to Sea. The setting is memorable and atmospheric, the exploration of the island reveals rich and interesting aspects of Azlanti lore, there's a wide variety of encounters (diplomatic, combat, and problem-solving), and the plot is interesting. I do think it's pitched a couple of levels too low, and I would recommend characters around level 8 that (hopefully) have a diverse range of knowledge skills.