The "Underwater Combat" section of the Combat chapter (PHB, p. 198) reads:
A ranged weapon attack automatically misses a target beyond the weapon's normal range. Even against a target within normal range, the attack roll has disadvantage unless the weapon is a crossbow, a net, or a weapon that is thrown like a javelin (including a spear, trident, or dart).
The Sharpshooter feat (PHB, p. 170) reads:
Attacking at long range doesn't impose disadvantage on your ranged weapon attack rolls.
With both of those in mind, would a PC with a Hand Crossbow and the Sharpshooter feat be able to shoot further than 30 feet underwater?