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Prescription Dive Masks for Free Diving

Why do i need a prescription dive mask for freediving?

Freediving, also known as breath-hold diving or skin diving, allows the diver to explore the the underwater world without the burden of scuba gear. Experienced free divers can hold their breath for more than 10 minutes. Herbert Nitsch holds the current world for deepest free dive, over 200 meters deep.


There are many reasons to freedive, besides competition. Bubbles from scuba tanks and regulators can scare away fish and other life that are noise averse. Some enjoy the freedom of moving through the water unencumbered by equipment.  Spear fisherman, who want to minimize the distance between themselves and their prey, frequently free dive instead of scuba. While spearfishing while scuba diving is not illegal in the United States, in many other parts of the world, it is due to the concerns for damage to coral reefs. 

Whether you are struggling to see your depth gauge/freediving watch or need help seeing the fish, a prescription freediving mask can improve your overall freediving experience. 


If you are freediving already, you are probably aware of the unique needs when considering a mask specific to free diving. Vision options, for free divers who need lens correction can also affect mask choice. If you are freediving and need help seeing clearly, a prescription freediving mask if for you. 

Herbert Nitsch, current world record holder for deepst free dive.

Which freediving mask is best for prescription lenses

Atum Free Diving Mask with prescription distance lenses.

prescription considerations for freediving masks

Stonger prescriptions, specially high plus lenses, require more space is the mask. This can be countered by using a smaller lens, like in the MP208 dive mask as another factor on lens thickness is lens size. If your prescription is very strong, you may need to go to a higher volume dive mask. 

Scuba diving masks and freediving masks share many characteristics, and in fact many people use freediving masks for scuba. Both sports require a mask with tempered glass lenses and sturdy construction.

The biggest concern for freedivers is volume of the mask. As divers descend, they must add air (through exhalation) into the mask to counter the pressure exerted onto the airspace in the mask.  Mask squeeze, occurs when air is not added. Masks with larger volumes, require more air to counter mask squeeze, air that would limit the freedivers bottom time. Pictured on the left is an ultra low volume mask, the IST Mp208 Atum mask with prescription distance lenses installed. 

Features of a quality freediving mask

  • Tempered glass lenses
  • Low volume 
  • Comfortable Strap
  •  Strong Construction

Freediving mask recommendations from see the sea rx

Top choice- MP208/ Atum Mask


MSRP: $65.00 + Lenses

The Atum mask is the most popular prescription-able freediving mask on See the Sea. The Atum features quality high end silicone, frameless design, low volume, and tempered glass lenses. 

The Atum is suitable for all our lens types including reading lenses, bifocals, and single vision distance and can correct for astigmatism, double vision, and other needs requiring custom lenses.

Distance lenses start at $208.00
Bifocals start at $285.00


Runner up- Hunter mask


MSRP: $49.99 + Lenses

For those that want a slightly larger volume mask, the Hunter mask is available for a slightly lower price with the same grade of silicone (but in a framed design instead of frameless). 

The hunter has also slightly larger lenses for a bit more viewing area which will be appreciated by divers who want reading only lenses at the bottom of the mask. The hunger volume is slightly larger than traditional freediving masks, but it is still a low volume mask ideal for those whose prescriptions would be limited in the Atum. 

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Scuba Diving with Astigmatism

Scuba Diving with Astigmatism

If you wear glasses, you may wonder what options are available to you for scuba diving or snorkeling. Specifically, if you require cylinder correction for astigmatism, can scuba diving masks or goggles accommodate your visual needs while scuba diving with astigmatism?

In our post, we will cover:

  • Basics of astigmatism
  • Reading your prescription
  • Options for scuba diving with astigmatism

If you already know you want one of our prescription diving masks which can correct for astigmatism, from See the Sea RX, the leaders in underwater vision, click the button below to see our order page.

Order an RX Diving Mask with Astigmatism Correction

If you want to read more information about diving and astigmatism, keep on reading!

What is Astigmatism?

Astigmatism was first described by Thomas Young, who noticed his vision problems when he was only a student, and he released his report in 1801. George Airy obtained the first corrective lenses (cylindrical lenses)  in 1827. 
Simply put, astigmatism, is an irregular shape of the cornea causing various vision problems including distortion or blurred vision (refractive error). The underlying causes are not completely understood, but scientists believe genetics play a large role in the formation of the condition.

Astigmatism, the Eye, and Diving

Understanding your Prescription for Astigmatism Correction

Most of us have two eyes, and our doctors have to distinguish what corrective lens belongs to each eye. Some prescriptions make this simple by using R or Right for the right eye and L or Left for the right eye. Other prescriptions use the terms OD & OS.

OD and OS are Latin abbreviations:

  • OD- Oculus Dexter- Right Eye
  • OS- Oculus Sinister- Left Eye


There are several other fields on your prescription which are important when ordering a prescription dive mask. 

Sphere (SPH)

The sphere is your lens power vision, displayed in diopters. The sphere can be negative or positive, and the distinction is very important. Negative sphere powers correct for nearsightedness. Positive sphere powers correct for farsightedness. 

If your sphere power is greater than +/- 4, you may want to consider our high index glass options in our dive masks for scuba diving or snorkeling as the lenses become thicker as the power increases. At +/- 6, we require the use of our high index glass (+$60.00). 

The correction is equal in all meridians of the eye, meaning the lens is spherical. The sphere power does not correct for astigmatism. The cheaper premade dive lenses are only available in sphere powers, and do not correct for astigmatism.

Cylinder (CYL)

The cylinder described the lens power for astigmatism and this is one of the critical measurements to have when scuba diving with astigmatism. Like sphere, the cylinder correction is preceded by a positive or minus sign. 
The cylinder, unlike the sphere of the lens, is not distributed equally throughout the lens, but is curved in such a way to correct for the incorrect curvature of the cornea. See the Sea RX’s prescription dive masks are able to incorporate the cylinder correction of your prescription to ensure you can see clearly underwater.

If your prescription lists no value or SPH/Sphere written under cylinder or CYL, your doctor has not prescribed any astigmatism correction for your corrective lenses. 


Unlike Cylinder and Sphere, the Axis is not a power or standalone correction, but a description of how the cylinder correction should be implemented on the lens. The Axis, measured from 0-180 (standard protractor scale). In simple terms, the axis describes how the lens should be turned prior to insertion into the mask to ensure you can see correctly while diving with astigmatism.

Options for Scuba Diving with Astigmatism

Prescription Dive Mask

If you want to scuba dive or snorkel with astigmatism, our dive masks include cylinder corrections and can help ensure you see clearly while diving. We construct our prescription dive mask lenses out of glass and guarantee them for life. 

Contact Lenses

Wearing contact lenses helps millions of people see daily without the bulk of glasses. Lots of divers report being happy to wear contact lenses while diving; however there are several concerns with contact lenses and diving.

Specially during your dive training, you will have to flood your mask multiple times which can result in a lost lens which would be catastrophic for individuals with severe optical corrections. There are also potential risks of infection.


Order an RX Diving Mask with Astigmatism Correction


Additional Reading:

How to choose a dive mask for prescription lenses   

More about astigmatism