Sunday Divers

Now you can learn to dive at home. No, not in the bathtub -- on the sofa. Fast Start Scuba is designed for would-be divers whose busy schedules preempt the required hours of classroom study. The course lets you study on your own time and work by phone with an instructor, who administers quizzes and monitors your progress. Then you can take the final exam, complete the calm- and open-water training and get certified at one of 350 resorts in the United States and the Caribbean. The course meets the standards of the PADI (Professional Association of Diving Instructors), the organization that certifies 72 percent of divers worldwide. The home-study kit costs $99, including textbook, dive tables, work sheets and quizzes; boat and equipment rental for the water training can run as high as $300, depending on the resort. Call 1-800-527-8660 for more information. Mosquito Coasts

An outbreak of St. Louis encephalitis has been plaguing central and southeast Florida since September, and residents and tourists alike are being urged to take precautions.

More than 70 confirmed cases of the disease, which was first recognized in St. Louis in the 1930s and is spread by mosquitoes, have been reported in 22 Florida counties, including several fatalities. Authorities are urging residents and visitors to:

Avoid outdoor activity at night, especially during the mosquitoes' peak activity periods (dusk and dawn).

Cover up and apply an insect repellent containing Deet to both skin and clothing when going out at night.

The Florida Department of Commerce has set up a recording with the most current information on the outbreak: Call 904-488-6397. For more information about the disease, call the Centers for Disease Control in Atlanta, 404-332-4555 (dial 1 for general information, 9 for viral diseases and then 3 for disease information). Visa Revisions

Following Czechoslovakia's lead in May, Bulgaria and Hungary have recently abolished visa requirements for American passport holders. Visits to Bulgaria (and Czechoslovakia) of fewer than 30 days no longer require a visa, while in Hungary, visits of up to 90 days are now visa-free. Poland and Romania still require American travelers to have visas. For more information about the recent changes, call the individual embassies: Bulgaria, 202-483-5885; Czechoslovakia, 202-363-6308; and Hungary, 202-362-6730. TRAVEL TRIVIAWhere is the only living coral reef in the continental United States? ANSWER BELOWTRIVIA ANSWER: THE FLORIDA REEF TRACT, OFF KEY LARGO.END NOTESADVISORY WATCH

Recent warnings from the State Department include:

Yugoslavia. Travelers should exercise caution, especially in Kosovo province (where clashes between police and demonstrators have resulted in fatalities and where Americans have been arbitrarily arrested, searched and detained) and in Croatia.

Guatemala. Caution is advised, with continued encounters between security forces and guerrillas leading to terrorist incidents in some parts of the country. Travel at night and on secondary roads should be avoided.

India.In New Delhi and other parts of northern and eastern India, political unrest continues to increase. Travelers should exercise extreme caution, and check the Citizens Emergency Center (see below) for details.

Bolivia. Isolated terrorist incidents against Americans have occurred, so travelers should exercise caution.

For details, and the most current information, contact the State Department's Citizens Emergency Center, 202-647-5225.