Bar Mar, the huge restaurant on the ground floor of the new Bank of America Tower, is a snacker’s paradise. There you will find tiny cones topped not with ice cream but with smoked fish, and tacos that wrap hamachi, caviar, and cured Spanish ham in a sheet of crisp nori seaweed. Most fanciful of all are Neptune’s Pillows: Little puffs each just the size for a Barbie doll to rest her head on. With a spicy tuna filling and a sliver of fresh tuna over the top, they’re like Totino’s Pizza Rolls reimagined by a sushi chef — gooey, crunchy, and all kinds of fun.

If you’re lucky, you might even snag a barstool during happy hour to enjoy your snacks along with a tangy margarita topped with salty foam. But don’t count on it. When the quitting bell rings, the 6,000-some workers in this building yabba-dabba-doo themselves down the elevator and pour into Bar Mar, making it the most boisterous and solidly packed new watering hole in the Loop since forever.

With its 40-foot-high windows, giant kraken sculpture suspended midair, and spectacular riverfront patio, Bar Mar is the centerpiece of a three-restaurant set from renowned Spanish chef José Andrés in partnership with Chicago’s Gibsons Restaurant Group. Below it is Café by the River, with breakfast pastries and lunch sandwiches, and above it is Bazaar Meat, a luxe steakhouse where you pay up to $55 per ounce for wagyu beef and order “say when” caviar service. (In River North, he has also recently opened the tapas bar Jaleo and cocktail lounge Pigtail.)

Of the three conjoined restaurants, Bar Mar finds a middle ground with its seafood-focused menu of one-bite marvels, oysters, ceviche, and shareable plates. It feels like more than a tapas bar but just an entrée or two shy of convincing me it works as a full-service restaurant. Snacks rule here, and your best move is to gather a group for drinks and bites knowing there’s another stop in your future. If you are planning to make a meal of it, then overorder. Portions are a fair bit smaller than prices would indicate.

Andrés has become better known of late for his humanitarian work with World Central Kitchen, parachuting in to feed people displaced by wars and natural disasters. But he made his name as a one-of-a-kind cook who combines playfulness and finesse to create memorable moments at the table. One of the last blockbuster chefs of the prepandemic era, he is now empire building, with two new places in Los Angeles and one coming to a certain hotel in downtown Washington, D.C., that has reflagged as the Waldorf Astoria. He is apparently eyeing Japan and Taiwan next.

In Chicago, chefs Alex Pitts (who oversees the whole enterprise) and Daniela Romero (who’s in charge of Bar Mar) keep this particular high-volume operation humming between Andrés’s visits. They pull off his modernist showboating with aplomb. Summon the rolling cocktail cart and order a Caipirinha whipped into frozen slush with liquid nitrogen. It smokes like witches’ brew but tastes more like high-proof sorbet than eye of newt. With it, you might enjoy the crunchy, fish-shaped Everything Bagel Airbread, filled with cream cheese and adorned with Russ & Daughters smoked salmon. This fanciful package arrives cradled in a 3D-printed yellow vessel.

Signature tapas from sister restaurant Jaleo make an appearance. Pan con tomate is usually a sure thing in any Andrés joint, though humidity seems to have robbed the imported Cristal bread of its all-important shattery crust. Calamari tempura, however, is a master class in crunch.

There are well-buttered little rolls, each about six inches long, filled with tender lobster or — for a retro take on Sloppy Joes — beef Bolognese. There are oysters on the half shell, platters of Spanish ham and cheese, and a classic Peruvian ceviche of grouper served with sweet potato and onions. Pass, bite, sip. Pass, bite, sip. It’s an enjoyable blur.

The one dish that makes me stop and take notice is a completely wacko and toe-curlingly delicious salad of frilly red and green seaweed and ripe cubes of papaya over olive oil yogurt. Toasted sesame oil brings these unlikely foodstuffs together into a singular genius flavor. Nearly as good is a salad of Brussels sprout petals and fruit set under what appears to be shaving cream but is in fact something Andrés calls “lemon air.” God bless those iSi foam whippers.

Even the large plates are made for sharing. Another Andrés classic, rossejat, is a deeply flavorful paella made with toasted fideos noodles instead of rice and served with sweet shrimp and blobs of aïoli. A whole Gulf snapper arrives at the table as six crunchy fish fingers served atop its batter-fried backbone. Sure, it’s great. Fried fish is great. And look, there’s tartar sauce! But a part of me wished this lovely snapper, its flesh so fresh my teeth stuck together, had gotten a more elegant treatment.

So here’s my beef: Bar Mar presents itself as a serious seafood restaurant, but most of the fish is no better than what you’d find in any decent sushi bar or steakhouse in Chicago. I never encountered any daily specials on my visits, or any indication that fish has seasons, or oysters identified by where they grow. You’d think an international outfit like this would make more of a point of shipping great fish to the Third Coast. When there is something of quality, like that snapper, it gets a lowbrow treatment, rather than a more refined approach. In a phone conversation, Pitts told me that the restaurant will run specials but isn’t sufficiently staffed to offer them routinely.

In the meantime, Bar Mar is living up to its mission of pleasing crowds. I’m sure I’ll be back with out-of-town guests, or before a show at the Lyric Opera, or when “5 o’clock somewhere” means 3:30 in Chicago and a Salt Air Margarita is calling my name.