No, underwater beach hockey was not played on the coast of Spain. The sport of underwater beach hockey is not a widely recognized or established sport, and there is no record of it being played on the coast of Spain. Beach hockey is typically played on the sand, and the addition of underwater elements would be unusual for the sport. **

In 10-meter underwater swimming, athletes dive into the water and swim as far as they can without taking a breath. The goal is to cover the longest distance possible underwater before resurfacing. Athletes use a combination of breath control, efficient swimming technique, and underwater propulsion to maximize their distance. It requires a high level of physical fitness, breath-holding ability, and mental focus. **

Swimming in a pond with your head underwater can be a peaceful and immersive experience. The sensation of the water surrounding you and the muffled sounds create a sense of tranquility and isolation from the outside world. It allows you to focus on your movements and the rhythm of your breath, making it a meditative and calming activity. However, it's important to always be cautious and aware of your surroundings when swimming with your head underwater to ensure safety. **

It is possible for some individuals to experience headaches after swimming underwater for 15 meters. The pressure changes and the exertion of swimming can lead to headaches in some people, especially if they are not accustomed to the activity. It's important to listen to your body and take breaks if needed, and to seek medical attention if headaches persist or worsen. **

Underwater, there is a whole different world teeming with life and activity. Fish swim gracefully, coral reefs provide homes for a variety of marine creatures, and plants sway with the currents. Predators hunt for prey, while prey try to avoid becoming a meal. The underwater environment is also affected by factors such as temperature, pressure, and light, which all play a role in shaping the unique ecosystem beneath the surface of the water. **

Seeing double underwater with swimming goggles can be caused by the refraction of light as it passes through the water and the curved lenses of the goggles. This refraction can distort the image, causing objects to appear duplicated or blurry. Additionally, the water pressure against the goggles may also affect the way light enters the lenses, further contributing to the double vision effect. Adjusting the fit of the goggles, ensuring they are properly sealed, and choosing goggles with flat lenses can help reduce or eliminate this issue. **

It is generally not allowed to film underwater in a swimming pool without prior permission from the pool management or owner. This is because filming underwater can raise privacy concerns for other swimmers and may also violate the pool's rules and regulations. It is important to always check with the pool management or owner before filming underwater to ensure that you are following the appropriate guidelines and obtaining any necessary permissions. **

People who enjoy underwater activities and challenges, such as swimmers, scuba divers, and water sports enthusiasts, may like to do underwater diving challenges in the swimming pool. These challenges can include holding one's breath for an extended period, retrieving objects from the pool floor, or navigating obstacle courses underwater. It can be a fun and challenging way to improve swimming skills and overall fitness. **