The pearl diving business was a key industry prior to the discovery of oil reserves. According to a source about pearling, the Persian Gulf was the best location for pearls. Pearl divers dive for one to three minutes and would have dove up to thirty times per day. There were no air tanks and any other sort of mechanical device was forbidden. The divers had a leather nose clip and leather coverings on their fingers and big toes to protect them while they searched for oysters. The divers were not paid for a day's work but received a portion of the season's earnings.