What is the difference between nearsighted and farsighted lenses?

Nearsighted (myopia) lenses use negative SPH values to correct distance vision. Farsighted (hyperopia) lenses use positive SPH values to help with close-up vision.

How do I find the sphere (SPH) value on my prescription?

Look for SPH or Sphere. It can also be labelled Power or PWR. A minus sign (-) is nearsighted and a plus sign (+) is farsighted.

How should I adjust my prescription for clear vision underwater?

For most people, choose 0.50 diopters weaker (towards zero) than your normal SPH, then select the closest available 0.50 step. This helps because water creates natural magnification and mask lenses sit further from your eyes than glasses.

I have astigmatism (CYL). What should I choose?

Use your SPH (sphere) for each eye. For CYL (astigmatism), the sign does not matter, use the CYL magnitude. Nearsighted (minus): CYL 0.00 to 0.75 start 0.25 to 0.50 weaker than SPH; CYL 1.00 to 1.75 start at SPH or 0.25 weaker max; CYL 2.00+ start at SPH for comfort. Farsighted (plus) lenses come in whole steps only (+1 to +5). CYL 0.00 to 1.75 round down to the nearest whole number for comfort. CYL 2.00+ round to the nearest whole with a comfort tie break: if SPH ends in .25 or .50 round down, if SPH ends in .75 round up. Special case: if SPH is +0.50 or +0.75 start at +1.00. More help: https://oceansoptics.com/pages/choosing-prescription-snorkel-mask-lenses-with-astigmatism

I can’t find my lens strength in the dropdown. What should I do?

The dropdown shows all available strengths for that mask. If your exact number is not listed, choose the closest available option using the guidance above. Upload your prescription or email info@oceansoptics.com if you want us to confirm the best match.

Can I choose different lens strengths for each eye?

Yes. You can select different strengths for left and right eye and mix and match any combination available in the dropdown.

How do I upload my prescription during checkout?

On the product page you can optionally upload your prescription so we can check your selection before we build it. You can also leave a note in the cart or email info@oceansoptics.com.

How do I stop my mask from fogging?

Try the toothpaste trick: rub a small amount of toothpaste on the inside of each lens in circular motions for a few minutes, then rinse thoroughly. Repeat if needed. Before each session, you can also use a tiny amount of baby shampoo or dish soap mixed with water, rub a thin film on the lens, then lightly rinse.

Do you have a guide to help me use my mask properly?

Yes. Mask 101 guide: https://cdn.shopify.com/s/files/1/0798/8055/2781/files/Mask_101.pdf?v=1728895468

What happens if I accidentally choose the wrong lens strength?

Message us as soon as possible. If the order has not entered the build or shipping stage yet, we can usually update the lens selection.

Are your lenses safe for both snorkeling and scuba diving?

Yes. Lenses are HD tempered glass and suitable for snorkeling and scuba diving up to 100 ft (30 m).

How long does delivery take, and can I track my order?

Most orders arrive in 5 to 10 days, but allow up to 14 days to be safe. Tracking is provided by email once shipped.

What is your return or exchange policy for prescription masks?

You have 30 days from delivery to request a return, as long as the item is unworn, unused, with tags, and in original packaging. See the return policy on the Oceans Optics website for full details.

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Rx Obsidian Farsighted Prescription Snorkel & Scuba Dive Mask

Name: Rx Obsidian Farsighted Prescription Snorkel & Scuba Dive Mask
Brand: Oceans Optics
SKU: ObsidianFar-Black/Black
Price: 85.0 USD
Availability: InStock

Rx Obsidian Farsighted Prescription Snorkel & Scuba Dive Mask

Quantity

$85.00 USD

SALE Sold out

Shipped with Care. No Hidden Fees. Just Clear Vision Ahead.

Mask Description

The Obsidian Corrective Mask for farsighted adventurers who want clear underwater vision with a comfortable, confidence building fit.

Featuring corrective lenses tailored to plus (hyperopia) prescriptions, this mask helps you see gauges, dive buddies, and the details in front of you without straining.

The clear silicone skirt creates a snug, comfortable seal while letting in light for an open feel. A wide peripheral view means you stay aware of what is happening around you, and the easy release buckles plus soft nose pocket make equalizing simple at any depth.

Ideal for farsighted explorers who want dependable clarity and comfort beneath the surface, the Obsidian Clear is built for relaxed, focused underwater moments.

Farsighted (plus) lenses for the Rx Obsidian are currently in production. Join the waitlist to be first to know when ordering opens, with expected dispatch in late January to early February 2026.

Prescription Lens Info

This mask features Farsighted (SPH) lenses in positive diopters (e.g., +1.00, +2.00, +3.00, +4.00 and +5.00).

Tempered glass lenses for strength, safety, and clear underwater vision.

Need help? Chat with us or email info@oceansoptics.com

Mask Sizing Chart

How to measure your face for a prescription mask (width & height)

Rx Obsidian

Size Category: Medium - comfortably fits most face shapes.

How to measure

1 Width: straight line from outer eye corner to outer eye corner (do not wrap).
2 Height: from just under your nose to just above your eyebrow line.

Mask Sizing Ranges

Switch to cm Switch to in

	Min (in)	Max (in)
Width	3.46 ″	5 ″
Height	2.75 ″	4 ″

	Min (cm)	Max (cm)
Width	8.8 cm	12.7 cm
Height	7 cm	10 cm

Options: Farsighted lenses · Face seal in Black or Clear · Frame colors: Black, Blue, Red, Yellow, Aqua, Pink · Optional action-camera mount.

More than JUST Free Shipping!

Orders $70+ ship free. Every order is carefully packed with quality guaranteed. Fast, trackable delivery in 5–10 days.

30 Day FREE Returns

Take advantage of our 30 days from delivery FREE return policy—shop with confidence. See our full return policy for more info

More than JUST a Guide!

Snorkelling 101 is Your Ultimate Guide to Better Aquatic Adventures!

Now free with every order! Access your eGuide instantly after checkout or via email, and dive in at your own leisure.

View full details

Use Our Exclusive Underwater Lens Calculator Tool

Underwater, light bends differently and can make your usual prescription feel too strong.
We lower it slightly to prevent overmagnification and keep your vision clear. Step 1: Enter your prescription to determine your recommended underwater vision

Right SPH (OD)

.

CYL:

Left SPH (OS)

.

CYL:

Suggested Lens Strength:

Right

Left

How to account for Cylinder?

Start with your SPH value, then adjust based on your CYL level

Farsighted (Plus +)

Our farsighted lenses come in whole number steps only: +1.00, +2.00, +3.00, +4.00, +5.00

Your CYL	Recommendation
0.00 – 1.75	Round down to nearest whole number for comfort
2.00+	Round to nearest whole number with comfort tie-break: • If SPH ends in .25 or .50 → round down • If SPH ends in .75 → round up

Special Case: If your prescription is +0.50 or +0.75, we recommend starting with +1.00 for optimal underwater vision.

Want detailed examples and explanations?

Read Our Complete Lens Selection Guide

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Rx Obsidian Farsighted Prescription Snorkel & Scuba Dive Mask

Rx Obsidian Farsighted Prescription Snorkel & Scuba Dive Mask

Mask Description

Prescription Lens Info