Yes, SCHNORKEL is a Scrabble word!

Letter values in Scrabble US: S 1, C 3, H 4, N 1, O 1, R 1, K 5, E 1, L 1.

Is it a valid word?

SCHNORKEL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time

Also: snorkel breather.

Not playable in Scrabble US: SCHNORCHEL.