A dinner at FIN begins with these guidelines: The menu changes regularly, plates are meant to be shared and will arrive at whim, the top half of the menu is raw, the bottom half is cooked. Then, maybe you're told the special, drink orders are taken, and your bathysphere is un-moored.

FIN is all about fish. A meal here is a plunge into a piscine paradise, except all of the sea creatures are fresh-dead and transformed into a kind of briny edible art by Chef Trent Pierce and crew. It's as if the cast of The Little Mermaid had met a perfect end in the open kitchen, and while you may find that image off-putting, rest happy knowing it's okay to eat fish because they don't have any feelings. (Thank you, professor Cobain.)

The restaurant approaches fish with care and honor. Every dish hitting the table feels full of intention. On the whole, that intention means a delicious meal. Yes, there are some hiccups, but not enough to ruin the experience.

While great care has been taken to use every usable space while maintaining some semblance of privacy and comfort for guests, FIN still has the close quarters of a nuclear submarine. The decor rests somewhere between Tokyo and Paris, with a touch of Crate and Barrel to keep it grounded. My struggle in describing it is likely due to my captivation with the food.

Given the finicky nature of fish and their focus on sustainable fisheries, FIN's dishes (and prices) tend to change constantly. It's difficult developing long-term favorites, which is a shame, because there's plenty to get hooked on.

One evening the "raw" side offered spicy octopus, wrapped in thin-sliced marlin, topped with a dollop of flying fish roe, a trio of which arrive in shallow soupspoons. Wrestling for the odd piece is inevitable after experiencing the creamy raw marlin, followed by octopus snap and the occasional pop of roe. With a flavor profile moving from bright, sweet, tropical fruit to a faintly bitter finish, it's quite good. However, more spice would give it the punch it deserves.

Much of the raw side is just as good, if not quite as complex. Uni is perfectly creamy—balanced with citrus and a touch of smoky trout roe. Thin sliced boquerones are excellent, topped with olive, tiny bits of potato, and a strange rosé gelatin for interesting texture, the ingredients barely balancing the aggressive flavor of the fish.

One evening the ceviche arrived from a world of "Thai flavors," including a bit of sesame, lemon grass, and daikon, along with cilantro and a bright sauce reminiscent of melted lemon sorbet.

On another night, a tiny, ridiculous, and pleasing Kumamoto oyster shooter sported a cava rinse and toppings of seared foie and roe. The result? A moment of buttery, briny delight.

Finally, while the striped marlin carpaccio was tasty, I'll admit it was the least appetizing of the raw dishes, looking like rubber novelty vomit. Luckily I'm unfazed by such things.

There are no such presentation flaws in the "hot plates" portion of the menu, but once deep into the selections, it can become difficult to reconcile sharing with price.

Which is not to say the citrusy, sweet-and-savory seasonal veggies perched atop a carrot puree aren't perfectly flavorful. They are. It's just that the single bite available after halving it with my tablemate might not justify the $11 price point.

The same feeling arises with a $15 scallop dish. Again, while the flavors here are very good—tarragon being particularly lovely beside thin golden enoki mushrooms—there is just too little there. It didn't help that the scallop was just a tad overcooked. FIN's menu demands nothing less than perfection.

Perfection is there. Consider squid ink tagliatelle with pickled calamari and flying fish roe. This is an amazing dish. The pasta is spot on, the textures are dynamic, and the flavor has depth and balance with just a touch of smoke and heat from a kind of habenero/bonito butter sauce.

The butterfish is also amazing, its dark dusting of cocoa yielding beneath the fork to reveal bright white flesh. Paired with mandarin orange slices, fennel, and balsamic, it's a dish both surprising and completely satisfying.

Which is all to say the biggest disappointment of a trip beneath FIN's waters is that it's over much too soon, and the pleasure of taking the journey costs a tad more than one might hope. It's a problem that could be remedied by FIN's kitchen nailing every single dish, and maybe placing the onus of enjoyment on the diner. It would behoove FIN's bright and helpful servers to add one more guideline at the beginning of the meal: Savor it.