What is the length (in inches) of the tube?

21.5 inches from the start of the tube wrapping around and up to the top and 16.75 inches from the bend in the tube to the tip

Will this fit over a full size dive mask?

You could adjust the snorkel to go over a full size maks, I think. However, it would fit over your area of vision. It would be awkward and not stable, I think. This is really for use with goggles, to my way of thinking. For a full dive mask, I want the snorkel on the side, not in front of my mask. I purchased this for kick-board exercises. I really want to focus only on my kicks & not have to breathe side to side. This is a really nice snorkel.

What is the length (in inches) of the tube?

18" to where it curves almost 90 degrees for the mouthpiece + 2 inches to the gray month.

When head goes underwater to lap with snorkel fill with water?

I don't have that issue. As long as the whole snorkel doesn't go under with your head, you wouldn't run the risk of you sucking water through it like a straw.

ASIN	B00KRNBO6Y
Batteries Included?	No
Best Sellers Rank	#14,174 in Sporting Goods ( See Top 100 in Sporting Goods ) #19 in Diving Snorkels
Brand	Speedo
Color	Shocking Lime
Customer Reviews	4.5 4.5 out of 5 stars (2,939)
Date First Available	26 February 2015
Department	unisex-adult
Included Components	Snorkel
Is Discontinued By Manufacturer	No
Item model number	USXBULLETHEADSNRKL
Manufacturer	Speedo
Material Type	silicone
Number of Pieces	1
Product Dimensions	2.54 x 2.54 x 2.54 cm; 113.4 g
Size	One Size
Sport	Swimming
Style	Swim Training Snorkel Bullet Head
Team	Speedo
Weight	1 Pounds

Speedo Unisex-Adult Swim Training Snorkel Bullet Head

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