The perils, delights of Virgin Island golf

''How many balls are you down?'' is the question bandied about by passing golfers here at Mahogany Run golf course, where electric golf carts, a billy goat's balance, and supreme golf skills are mandatory.

The question is more serious than whimsical, and not just because the breezes over three seaside fairways (the world-famous ''Devil's Triangle'') more often than not suck your tee shot over the waves toward Cuba.

And it's not just the dime-size greens or ribbon-thin fairways that are often parched enough to add 20 extra yards to your slice or hook.

No, the reason you lose a lot of golf balls here - signs warn ''no more than five minutes to look'' - is that the ground rolls more than the ocean in a hurricane. The only flat lie at Mahogany Run is the score you tell your partner at the end of each hole.

Consequently, this course is a study in uphill, downhill, and sidehill lies, and what they do to a golf ball once it's airborne. If you've licked that problem, watch out for the steep bunkers or slopes protecting each green. Unless your ball has suction cups instead of dimples, chances are high that it will - for the sheer angle of terrain - carom into the bushes, trees, or shoals.

This has its advantages, of course - for both accomplished golfers and the weekend duffer like me. One of them is that the course demands discipline. You either learn the finer points or start repeating Robert Frost's ''Whose woods these are...?''

Another advantage is that when you stand beneath these beautiful mango, cashew, and palm trees, raking the underbrush with your 7-iron, you're likely to have company - even from the pro ranks.

Witness my partner, course pro Mike Dunavan, the straightest, most controlled shooter I've ever seen, who more than once missed the green by inches only to be faced with a considerable wedge shot rather than a short chip.

''The course steals your good shots,'' says this svelte, bespectacled pro of the course that one guide called the tightest golfing layout you will find anywhere. ''People coming from wide-open courses in the states can't handle what happens to them here.''

The guide also says, ''Figure on shooting 10 strokes above your norm.'' That's because of: (1)the trickiest greens I've ever played - highly varied in size, grain, and speed (four putts are common on No. 8); (2)scrubby, omnipresent rough that pinches the tiny fairways; and (3)trade winds, just enough to cool your face and play tricks with your shots.

The course has probably the most stunning views in all of Caribbean golf. Leave your big swing at home and come to relax, enjoy the salt spray, surf sounds, scenery, and yes, even stairs to some greens. ''Play it twice,'' says Dunavan. ''The first time is treacherous, the second enjoyable.''

Fountain Valley

While Mahogany Run often looks down at the sea, St. Croix's Fountain Valley looks up at the hills from its resting place at the bottom of a tropical valley well inland. This Rockresort-owned, former host course to ''Shell's Wonderful World of Golf'' was designed by the famous course designer Robert Trent Jones. Compared with Mahogany Run, Fountain Valley has wider, lusher fairways and bigger, more consistent greens. Along with its impeccable condition, this adds up to a more satisfying round of golf.

The course is simply more comfortable. Golf carts don't have to stay on special cart paths; you're not likely to fall over while trying to hit from nearly vertical slopes. And if you hit an accurate wood, long iron, or wedge shot you will be rewarded rather than arbitrarily penalized, as at Mahogany Run, where course designers Tom and George Fazio dynamited rock to open up areas for some greens.

But before I add to the chauvinistic banter you hear at both courses, I'll help silence the controversy by saying Fountain Valley and Mahogany Run are vastly different courses. Both are great in their own way.

When you walk down the fairways at Fountain Valley, you feel a spongy fairway beneath your spikes. Golf balls sit up and beg to be socked. Greens are smooth and lush enough to make your ball do what you told it to. All this does not mean the golfer is not challenged.

There are water traps on one-third of the holes, notably a lake from tee to green on No. 8. Fairway bunkers make No. 13, flanked by a water-filled gully that eventually cuts in front of the green, a treacherous par 5.

Dan Loucks, the head pro, calls his course the ''thinking player's course.'' This means that a variety of well-placed sand traps, bunkers, and water hazards keep players of differing skills thinking on each shot, not just the final approach. And because the course is more open, different challenges present themselves each time around. The Buccaneer

This resort course on the grounds of the island's largest hotel, the Buccaneer, has been maligned by at least one guide: ''This isn't a course for people who take the game seriously.'' But I'll go so far as to say it's definitely worth trying for 18 holes.

The course is short and hilly. There are plenty of doglegs, water-protected greens, and blind approach shots to make it challenging for both low and high handicappers. ''Even a good player has to make his shots,'' says golf pro Tim Johnson.

And there are wonderful hilltop vistas of the ocean. For all its splendor, Fountain Valley can't boast of that. The Buccaneer is much tighter, so there's also not so much room to spray your wood shots from side to side.

The front nine is more forgiving, says Johnson, a good preparation for what he has named his toughest three holes: The Bermuda Grass Triangle - Holes 14, 15 , 16. ''We lost a foursome in there once,'' says a beaming Johnson of the three holes wrapped expertly around a mangrove lagoon. The allusion, of course, is a cross between the Bermuda Triangle - where ships and planes are allegedly lost forever - and the course's Bermuda-style grass.

Perhaps not in the same league with the two other courses, the Buccaneer is still a challenging and scenic round of golf.

Practical information:

Greens fees for Mahogany Run are $24 for the public, $17 for hotel and condominium guests. Golf carts are mandatory and cost $18; club rental (Spalding Execs) is $10; shoes, $3. All hotels within 25 minute drive.

Greens fees at Fountain Valley - 12 miles west of Christiansted - are $20. Carts are $18; shoes, $5; and excellent rental clubs, $9. All hotels within a 35 minute drive.

The Buccaneer Golf Course greens fees are $12 for the public, $10 for hotel guests (subject to on-season rate increase). Cart rental is $17; club rental, $5 for nine holes, $8 for 18. Located right outside Christiansted; close to hotels.