It's the summer of the dauntless dollar, and planning -- and the need to make reservations -- have never been more crucial for travelers headed for Europe. Many hotels are solidly booked. In fact, you'd be wise not to leave home without written confirmation of a room.

But what if you choose to ignore all the warnings? Is there any chance of finding a place to sleep in Europe without a firm reservation? The odds are against you, but the situation isn't hopeless.

Your prospects as a spur-of-the-moment traveler will depend upon the city you choose, how particular you are about accommodations and plain luck.

In this banner year for European tourism, the European Travel Commission -- which represents 23 countries -- is predicting a 12 percent increase over last year's total of 5.8 million visitors. And that means many hotels in major cities are already fully booked for the season.

"I don't know anyone who's going without having at least the first night reserved," says ETC spokesman Hans Friis. "Planes usually arrive between 6 and 11 a.m. Most people want to clean up and rest after the long transatlantic flight and the time change. Most don't sleep well en route."

Washington-area travel agents agree there is a special need for the independent traveler to reserve ahead this summer. But they take their warnings a step further: Keep in mind that one night guaranteed in a crowded capital may be sufficient if you're planning to head for the countryside the following day -- after asking the concierge or desk clerk to call ahead to your next town and book another room. But if you plan to stay longer in the original city, you can't count on getting a second night at the same hotel -- or any other, for that matter.

So your best course of action is to book a place to stay before you go, which either international airlines or your travel agent will gladly do at the time you book your flights. (An added advantage of using agents is that they may have a contact abroad if you run into a problem at the hotel.)

If you do go without a reservation, hotel information is available in most of the major airports and train stations abroad, and often there's a booth manned by someone who will phone around town for you in search of a room. But you can't count on success. So it's wise to keep in mind that areas outside the always-popular capitals will most likely be less crowded. The young, single traveler without a fixed schedule -- who generally is more flexible, less demanding and wants to travel as cheaply as possible -- will have less of a problem than visitors who insist upon first-class, centrally-located hotels.

This is how the tourism offices of five countries view the hotel situation:

BRITISH TOURIST AUTHORITY: "In recent years Britain has received more than 50 percent of the American traffic to Europe," says Bedford Pace, public relations manager for BTA, and with the dollar so strong against European currency London is busier than ever this summer. Adding to the demand for rooms, the Wimbledon tennis matches begin at the end of this month, and 16,000 delegates are expected to attend the American Bar Association convention in July.

"I would always try to have my first night's accommodation booked," Pace cautions. For those who fail to heed that advice, London's Visitors and Convention Bureau operates a hotel booking service at Heathrow Airport and will try to find accommodations for a nominal fee (around $2). However, Pace says it's "unlikely you will get into any of the major hotels" in the capital through August -- unless you're very lucky. You probably will have to accept a room either within the suburban commuting area or possibly in a city hotel of a lower standard than American visitors usually find acceptable.

Gatwick Airport also has a booking service, but it's a private business not operated by the city's bureau and the hotels represented are limited to those that have paid a fee to be included on the list.

FRENCH GOVERNMENT TOURIST OFFICE: With conventions, exhibitions and other activities in Paris -- in addition to the heavy influx of tourists -- "from now until about mid-June is hopeless" if you have no reservations, says George Hern, director of public relations. "After that, most of the month of July is going to be very difficult and the first two weeks of August are heavily booked. September -- forget it. Even now it's utterly hopeless." It would seem this is not the best summer for a spur-of-the-moment trip to Paris.

The hotel information service at Charles de Gaulle and Orly airports "hopefully will tell you what to do -- like get back on the plane," says Hern. The best thing to do upon arriving in Paris without a reservation is to get on a train and go somewhere else -- perhaps to less-crowded regions like Burgundy or Normandy, or take the swift TGV express train to Lyon. "But not to the beaches," Hern warns. On the other hand, for visitors planning to see Paris in October, November and December, at the moment "it looks good."

GERMAN NATIONAL TOURIST OFFICE: "If you intend to stay in a major city like Munich this summer, it's not a good idea to come without at least one night reserved in advance," says Hedy Wuerz, director of public relations. Otherwise, you would have to go outside the city to find a hotel room, although some guest houses may be available fairly close in in the suburbs. City-operated offices at the Munich and Frankfurt airports give information on hotel availability and prices.

ITALIAN GOVERNMENT TRAVEL OFFICE: When you come without reservations you must be flexible, and not just during the current season. Often the busiest periods for cities like Rome, Milan, Florence and Venice occur from September through November, because that's when major trade events and fashion shows take place. This summer, rooms probably will be available in Rome and some other cities, depending on what category of hotel is sought.

Americans want to book deluxe hotels, officials point out, and those are already heavily booked in most major cities. Rome, with a large number of hotels in all categories, has upgraded many properties. Accommodations should be available in Venice (except in September); Florence is very tight, but there are many rooms in the surrounding countryside; Naples and Capri have no problem. In Rome both the national and city tourist offices operate airport booths to help visitors find hotels.

NETHERLANDS NATIONAL TOURIST OFFICE: Families and elderly travelers are advised not to come to Amsterdam this summer without reservations. Young people, who usually aren't particular about where they stay and are seeking inexpensive lodgings, are less likely to have a problem. An information desk is operated at Schiphol Airport by participating hotels and will try to find rooms for visitors who need help.

No matter what your destination, it's a good idea to find out from the tourism office if any major conventions, festivals or exhibitions are scheduled when you plan to be in an area. An influx of additional thousands of visitors to attend an event can only further complicate the hotel situation. For example, it's unlikely that the following cities will have a room to spare on the listed dates:

Salzburg, Austria -- July 3-25, the Bach Festival; Montreux, Switzerland -- July 5-21, the 19th annual International Jazz Festival; Edinburgh, Scotland -- Aug. 11-31, Edinburgh International Music Festival; Munich, Germany -- Sept. 21-Oct. 6, Oktoberfest.