Five of the 12 lines that traditionally sail in the Mediterranean during the spring and summer have either pulled out of that region completely for 1986, or altered their itineraries, in response to the recent terrorist incidents.

While those that remain reported that they are "sitting tight," many admitted that bookings are "significantly lower than last year." However, all said that, barring any further occurrences, they hoped to bounce back during the summer months.

Ocean Cruise Line, Princess Cruises, Royal Cruise Line, Royal Viking Line and Sea Goddess Cruises Limited have announced changes for 1986.

Ocean Cruise Line has cancelled its seven-day Venice to Piraeus sailings aboard the Ocean Islander, and will offer two different seven-day itineraries in Northern Europe from Copenhagen instead. However, the change is not in response to the violent incidents, according to a spokesperson for the line.

"We felt it would be more advantageous to base our ships in different parts of the world," he said, noting that the line's other ship, Ocean Princess, also offers Mediterranean cruises from Venice. "This way, we won't be competing with ourselves, and we can offer our passengers a wider variety of choices."

The line will continue to operate seven-day sailings from Venice to Nice, aboard the Ocean Princess. However, the ship will be calling in Malta, rather than Tunis this year.

Royal Cruise Line also has pulled its ship, Golden Odyssey, out of the Mediterranean, and repositioned it to the Orient and Alaska. The changes represent new destinations for the line, and the first time it has offered seven-day cruises.

Royal Cruise Line has also cancelled its March 27 cruises to the Holy Land and Greek Isles aboard Royal Odyssey, and substituted a call in Venice for Athens on that ship's remaining three Mediterranean sailings.

"Advance booking interest in Mediterranean cruises, particularly in the Eastern Mediterranean, are down significantly," said Richard Revnes, president of Royal Cruise Line.

"Preliminary research shows a high demand for the Orient and Alaska, and we're responding to this strong consumer interest."