THROW OUT A LINE: The 17th annual White Marlin Open is fast approaching: Aug. 6-10 off the coast of Ocean City, with organizers hoping for a record turnout. The Open, already the largest billfish tournament in the world, stands to pass the $500,000 level this year in prize money for catches of white and blue marlin, tuna, dolphin, wahoo and shark.

Last year's champion, Al Bednarik of Gambrills, is returning, looking to surpass the $170,000 he won last year for his 69-pound white marlin. Other returning winners: Virginia Beach's Kitty Falk and Jim Daniel of Salisbury. Last year, Daniel landed a 942-pound blue marlin, a state record, fishing on just a 28-foot boat.

Some rules of the game: Each boat is permitted to fish a maximum of three days, with late registration held at Harbour Island Marina in Ocean City on Aug. 4-5. The tournament is open to anyone and, although most boats have been more than 40 feet in length, many smaller vessels have been among the entries in recent years.

For more information, call (301) 289-9229. FLYFISHING MEETING: Longtime Potomac River bass fishing guide Ken Penrod will present a program on flyfishing for smallmouth bass on the Upper Potomac at the next meeting of the Northern Virginia Chapter of Trout Unlimited on Aug. 2. Penrod, who has fished the Potomac for more than 30 years, will offer a presentation on the best flies and the most productive areas and times. He also will discuss access points and the best spots for wading and floating.

The chapter's monthly meetings are free and open to the public. The latest meeting will begin at 6:45 p.m. at the National Wildlife Federation headquarters, 8925 Leesburg Pike (Rte. 7) in Vienna. For information, call George Brandon, 347-2654. SOVIETS IN CUP: The 17th annual running of the Yachting Governor's Cup on the Chesapeake Bay will be Friday and Saturday, Aug. 3-4, starting in Annapolis. Two groups of Soviets will participate in this year's event as part of an exchange program with Odessa Marine Institute. Also, the yacht "Fazisi," the first-ever Soviet entry in the Whitbread 'Round-the-World race, will include this event as part of its East Coast goodwill Tour.

Daylong festivities will be held at the St. Mary's College waterfront from midmorning until midnight each day. The public is welcome to attend these festivities, with admission $10 for adults, $5 for youths 13-20 and free for children 12 and under. For race information, call (301) 862-0291. All other information: (301) 862-0380. SEVEN DAYS ON A BIKE: Nearly 1,000 entries have been received for the second Cycle Across Maryland, starting Aug. 5 in Havre de Grace. The noncompetitive, seven-day tour goes for 350 miles through Maryland's horse country and farmland in the north to the Chesapeake Bay, with stops in Oregon Ridge in Baltimore County, Frederick, Columbia, Upper Marlboro, Waldorf and St. Mary's College in the south.

With 55-mile stages each day, there will be plenty of time for sightseeing and participating in events sponsored by each host site. Sponsored by the First National Bank of Maryland, Cycle Across Maryland will make a contribution to the American Lung Association from the money raised.

Registration includes a $110 fee, which includes camping space and shower facilities, daily transportation of cyclists' gear, a T-shirt, a tour book and medical aid and entertainment at each host site.

For more information, call 1-800-842-BANK. GUIDE TO BAY: "The Bay and River Guide," a 75-page, full-color guide to more than 750 boat landings, marinas and other public access points on the Chesapeake Bay and the Susquehanna River is available at Virginia Department of Game offices.

The guide costs $4.95 and is available by visiting or writing the Department of Game and Inland Fisheries, 4010 West Broad St., Richmond, Va., 23230. Make checks payable to the Treasurer of Virginia.