[Must Read] Diving at a very deep (-30m or more) with a diving mask you're using for the first time is dangerous!

【必読】初めて使用するダイビングマスクで直ぐ大深度(-30m以上)のダイブは危険!?
To ensure that you can enjoy diving safely, securely and enjoyably with your UMMY diving mask, we ask that both beginners and experienced divers be sure to read the following precautions.

Compatibility between the customer and the diving mask is very important in diving.
It's a very complex and sensitive issue.

Depending on the situation in which you use the mask, it may not necessarily be the best mask for you. Compatibility with the mask will vary depending on your facial structure, the tightness of the straps, your physical condition, and your skill level.

Therefore, even if you have experience in free diving, it is dangerous to start free diving at great depths (-30m) immediately after starting to use a new mask. When you first start using it, be especially careful to check the fit and follow the instructor's instructions and gradually increase the depth.

In addition, if your physical condition is poor, such as if your mask fits poorly or the straps are too tight, you may experience mask squeeze (mask being pressed against your face due to water pressure) or difficulty equalizing your ears, even at shallow depths, depending on your skill level. If mask squeeze does not go away even after blowing your mask (breathing out of your nose to return the mask to its original position), or if you are unable to equalize your ears and continue diving, you may suffer from internal eye bleeding, nosebleeds, headaches, or inflammation or rupture of the eardrum. If you feel any abnormality, immediately stop diving and, depending on the situation, seek medical advice.

Enjoy safe, secure and fun diving with UMMY!