In the middle of the ocean, surrounded by water, hydration can be the last thing water sports enthusiasts think about. That can be a dangerous oversight.

Saltwater and sun can quickly cause dehydration. Whether you are surfing, paddling, kite surfing, bodyboarding, free diving or long-distance swimming, dehydration can creep up on you, and when it does, it can bring some miserable symptoms and, in extreme cases, cause death.

The average adult loses more than 10 cups of water daily simply by sweating, breathing and eliminating waste, according to the Mayo Clinic Newsletter.

"You also lose electrolytes — minerals such as sodium, potassium and calcium that maintain the balance of fluids in your body," Mayo experts note. "Normally, you can replenish what you've lost through the foods and liquids you consume, even when you're active. But when you eliminate more water and salts than you replace, dehydration results — your system literally dries out."

Oddly, thirst is not an accurate indicator of dehydration. If you wait until you are thirsty to replenish your body fluids, you are already dehydrated. This can be even more serious among older folks who have a diminished ability to recognize thirst.

The best time to consume fluids is long before you are thirsty. Avoid drinks containing caffeine or alcohol while in the sun and choose healthy options, such as pure tap water.

ATHLETES NEED WATER

The onset of dehydration is especially scary for competitive ocean athletes.

"What we know is that within 10 minutes of really strenuous exercise in the ocean you will have the first effects of dehydration that will reduce your peak efficiency by approximately 10 percent," said Jim Howell, an avid water sportsman and operations chief for the city's Ocean Safety Division. He's referring to all-out racing mode, of course, not just an everyday swimmer or surfer heading out into the ocean.

"The first physical sign of dehydration a surfer will notice is foot cramping; it happens after just 1 1/2 or 2 1/2 hours, depending on your body," Howell said. "If you get a cramp, your surf session's over."

Paddlers and kayakers, he said, may get hand cramps and stiffening; "then your hands start to get stiff and you can still paddle but it will become more difficult, and cramping may spread to other parts of the body. That's the danger zone, when cramping spreads to other larger muscle groups like the abdominals."

Cramping begins in the ankles and calves for bodyboarders and bodysurfers, Howell said.

During a lifetime of ocean sports and lifeguarding, he has seen it all, he said, "and have experienced it all myself."

PROTECT YOURSELF

When involved in a sport that places you above the water, such as paddling or sailing, Howell recommends wearing a loose-weave shirt or one that wicks away the moisture. White is better than black because it reflects, rather than absorbs, the heat.

Surfer Jeannie Chesser always drinks at least an eight-ounce glass of water before she heads out into the surf.

Holger Gruenert of Kaimuki is an avid kite surfer. His hydration strategy is simply to drink a lot of water before he goes out into the ocean.

"I try not to drink coffee or it catches up with me real quickly. If I do, I offset it with plenty of water," Gruenert said. "You can last a few hours even in full sun if you start properly hydrated." Gruenert has tried different "sports drinks" but said he now sticks with pure tap water.

It's best to start hydrating the day before strenuous exercise, experts advise. Health advisers writing in the Mayo Clinic Newsletter note that producing lots of clear, dilute urine is a good indication that you're well hydrated.

"Two hours before an endurance event such as a marathon, drink two cups of water. One to two cups of water is usually adequate before shorter bouts of exercise," the Mayo experts advise.

It's easier for paddlers to keep a bottle of water with them in the canoe, kayak or one-man. However, when racing or making crossings, the paddler may not want to stop to drink. That's when a "camelback," or hydration pouch that can be strapped onto the back, comes in handy. It has a tube that comes around to the mouth so it's easy to access the water without the use of hands. Camelbacks are also useful for kayakers, stand-up paddlers and other ocean athletes.

The bottom line, Howell said, is that water is essential to good performance and well-being.

"You want to go out and have fun in the ocean, and if you don't hydrate you're not going to be able to do that," he said. "You won't perform as well."