Most of the countries including USA, UK, Ireland, New Zealand require a visa to enter the country. The single-entry visa is available at Muscat airport but, for multiple entries, you have to apply online in advance. A tourists visa is applicable for six months from the date of issuance, and it is valid for staying in Oman for thirty days from the time of entry.
For Indians, the visa is not available on arrival. Indians have to apply three to four weeks in advance on the official website.
Bahrain, Kuwait, New Zealand, Qatar, Saudi Arabia, UAE