COPENHAGEN - The sightseeing boat was half way down the cafe-lined canal when the pilot started back toward the pier. "We have to pick up more people," the guide said. As we neared the mooring, we started screaming.

"It's Sam!" In a city of a million people, the late-comers turned out to be companions on our 10-day Baltic cruise.

That free-wheeling ability to come-and-go-as-you-please had convinced our motley crew of 12 that a cruise vacation just might work.

It's not as if we're best friends since childhood, after all. We just met at Einstein's.

Here's how it happened: Often, The Husband and I would hit our neighborhood Einstein's bagel joint on Saturday mornings. He ran into former neighbors, who stop there most weeks. Eventually we sat and chatted. The group grew.

Three years later, a dozen-plus of us, ages 42 to 74, spend the Saturday coffee hour debating the state of the world _ political opinions vary wildly _ and sharing the struggles of child-rearing, aging parents and cranky feet. There's no set meeting time, no obligation. As a group, we rarely gather otherwise.

The Baltic cruise was ringleader John's idea, broached a full year before the sailing date. There were demurs: Bad economy, been there before, didn't like cruising. Eventually, only one regular couple bowed out.

Now here we were, wandering amid pastel row houses and the Danish royal treasury, chowing down on $20 burgers and $10 beers _ the exchange rate is vicious _ and visiting the temp-and-attitudinally cool Icebar before we joined "the hole gang" on our voyage to the capitals of northern Europe.

We sailed aboard the Crown Princess. Our 10-night itinerary would take us to Stockholm, Helsinki, St. Petersburg, Talinn, Gdansk and Warnemude (about 2 ½ hours from Berlin), then back to Copenhagen.

Before our trip, we'd traded research on ports and devised a plan. In most cities, we'd each wander at will. In the two most complicated ports, St. Petersburg and Berlin, we maximized our time and group-buying power by arranging private tours in advance. In Gdansk we opted for a ship-arranged walking tour. By night, we'd meet for dinner and trade tales from the day.

And except for a few minor mishaps _ Neha's turned ankle, my own lost luggage (reacquired before we boarded the ship), John's overnight bout with stomach distress (in these norovirus-prone times, he was quarantined for a day) and a bad sound system on our Gdansk tour _ things went according to plan.

In Stockholm, we split up, some taking off for the Vasa Museum, with its intact 17th century war ship, others for the colorful "old town" of Gamla Stan and the fantastic interiors of the City Hall, home to the annual Nobel Prize dinner.

In Helsinki, Donna and John _ recently released from his sick bed _ took a city tour with a guide they raved about. Determined to try the local cuisine, Bob and Lori set out for a reindeer lunch, where they ran into Judith and Bernard. Others hit arts sites _ the remarkable underground Rock Church, the Kiasma contemporary art museum and Wikstrom's striking Deco statues gracing the entrance to the Eliel Saarinen-designed train station. Neha invested $100 in a fox hat.

Talinn proved a medieval treasure box of long views across terracotta roofs and a sky pierced by spires. In our few hours in port, we scurried into Europe's oldest Gothic town hall, bargained for sweaters and shawls, slipped beneath the fanciful domes of the imposing Alexander Nevsky Church.

We caught Gdansk on the first day of the annual St. Dominic's festival, a 700-plus-year-old street fair with craft and food stalls and a parade of medieval knights and damsels. In 1989, when Poland overthrew Communist rule, the city had few shops, our guide told us; today the cobbled old town-streets are lined with boutiques specializing in amber.

But the highlights clearly were St. Petersburg and Berlin, where we'd arranged private tours for our longer-than-usual port stops.

Not that either was nearly long enough. We dashed from site to site, strolling at some, simply driving by others. To avoid long waits for lunch, we packed fruit and sandwiches from the breakfast buffets _ a real deal, when we discovered the unbelieveable price of just about everything in Europe.

Our two days in St. Petersburg were barely enough to make it to the most famous Tsarist haunts. At the spectacular Easter Egg-blue Catherine's Palace, we marveled at the majesty of gilt interior restored from mere rubble after World War II. Nearby Paul's Palace _ bypassed by most tours _ was a delicate jewel box of Wedgewood-like ceilings and inlaid floors. The sprawling gilded fountains of Peterhof, the elaborately painted vaults of St. Isaac's Cathedral and the Church on the Spilled Blood, the tombs of the Czars _ all went past in whirl.

Our three hours in the Hermitage offered a glimpse in the appointment-only Gold Room filled with antiquities, icons and imperial jewels, then on through the soaring halls to gaze at paintings by Da Vinci and Rembrandt and every master of Impressionism.

"I saw more Rembrandts, Gaugins, Matisses and Cezannes in one place than I've seen combined in my lifetime," said Donna, an artist. "I just couldn't believe it."

The 2 ½-hour ride from the ship to Berlin proved well worth it, thanks to guide Richard Campbell. For decades Campbell worked here for the U.S. government in jobs he never quite explained, and for most of the years of the Berlin Wall, his office sat on the second floor overlooking Checkpoint Charlie. His "back stories" added perspective to the smart modern architecture, the Reichstag and Brandenburg Gate, the new Memorial to the Murdered Jews of Europe (he's been inside Hitler's bunker, located nearby but closed), the remnants of the Wall and the policies that built and sustained it.

Less momentous, he took us to the ice cream stand considered the best in Berlin, and to the local "kaffee" chain called _ appropriately _ Einstein. Despite searing heat, we had to snap a photo.

We could have spent another day, or two. Or more. If our trip had one serious drawback, it gave us too little time to explore on our own.

But given the rate of exchange, we agreed, a cruise was the only reasonable way to see Europe just now _ at least in high season. With modest hotels priced $150 and up, a small bottle of water at $5 and an unremarkable dinner more than $50 without beer or wine, a similar trip on our own would have cost a small fortune.

Worse yet, a less structured trip might have cost our casual but coveted friendships.

"I knew it would all work out," Donna confided one night at dinner. "But what if it hadn't?"

___

CRUISING THE BALTIC

Many cruise lines offer Baltic itineraries. Our tip: Choose the one that allows the most time in the ports that are most important to you.

Prime time is July _ which means prices are highest, but weather is warmest. Baltic cruises typically are offered April-September. Details below are for July departures from Copenhagen. Prices are per person, double occupancy; taxes and fees add $150 per person. Most lines offer other Scandanavian itineraries as well.

_Princess Cruises: Our 10-day cruise aboard the Crown Princess (about 3,100 passengers) sailed from Copenhagen and included stops in Stockholm, Helsinki, St. Petersburg (2 days), Talinn, Gdansk and Warnemude (for Berlin). A similar Princess cruise next July starts around $2,000. www.princess.com.

_Our pick for best itinerary: Azamara, which offers offers a 12-day itinerary with two days in Stockholm and three days in St. Petersburg on the Azamara Journey (about 700 passengers.) July prices from $2,499. www.azamaracruises.com.

Cruises from seven to 12 nights are offered by most major lines, including Costa, Crystal, Holland America, Royal Caribbean, NCL, Hurtigruten (formerly Norwegian Coastal Voyage), MSC, NCL, Oceania, Regent Seven Seas and Silver Sea. For details on those cruises see www.MiamiHerald.com/travel.

VISAS: Visa requirements change, so do your homework. This summer, visas for Americans were required only in Russia for this sailing; however, Russia visas were NOT required for visitors taking ship tours nor for visitors taking pre-arranged tours by companies that offer blanket visas (contrary to what some cruise lines will tell you.) Before you fork out the cash for an individual visa, check with your tour company in Russia (not just your U.S. agent, who may not have the latest update.) If you must have an individual visa, consider VisaHQ (www.visahq.com, 800-345-6541), which we've used in the past.

PRIVATE TOURS: In St. Petersburg, we used Esperance, a Virtuoso agency, with superb results. They provided a great English speaking guide, comfortable bus, VIP entrance at sites and access to special rooms at the Hermitage and Peterhof. www.esperancetravel.com; fax (011-7-812) 332-6411.

Also highly recommended by readers: DenRus Tours, www.denrus.ru, and SPBT Tours, www.spbtours.com.

In Berlin, we worked with Richard Campbell, an American and former U.S. government specialist whose office in the 1960s overlooked Checkpoint Charlie. If you're a Cold War buff, he's your man. Campbell arranged transport in private mini-vans from the port at Warnemude (2 ½ hours each way) to Berlin and the city tour for about the same price as the cruise ship's transportation alone. rgc2012@yahoo.com.

USEFUL RESOURCE: Fodor's "European Ports of Call" outlines highlights suitable for port calls, along with details (though sometimes outdated) about getting from the dock to the town.