Chaos erupted at the Similan Islands ticket office after the area was re-opened for a limited number of visitors, according to local authorities.
Authorities have allowed access to the islands for the first time after a routine five-month closure to allow the area to recover from tourist numbers.
The number of visitors to the island has now been capped at 3,325 a day and the number of divers at 525, said the Similan national park office. Visitors who wish to visit have to purchase a ticket to enter the area.
The reopening on Wednesday saw chaos breaking out at the ticket office.
Queue cards were issued to staff of tour agents who were buying the tickets for their customers. To obtain the tickets, they are required to present copies of their customers' ID cards or passports.
The staff also must fill out the details of their companies and pay boat fees for entrance to the Similan Islands. The names of visitors on board the boats must also be listed.
The authorities said most tour staff did not understand the process, and some failed to produce the required papers to the officers, prompting intervention from the park chief.
Jaras Srisukkaew, a tour operator, said the confusion was caused partly by a newly-issued regulation which requires visitors to travel on the same boat as they were booked in. They cannot switch boats after they have purchased the tickets.
Mr Jaras said tour operators were left wondering if the boat-switching ban would still apply if a boat breaks down in the middle of the sea and passengers need to be transferred to another vessel.
Similan national park chief Ruamsin Manajongprasert said boats which malfunctioned on their way to or back from the island are permitted to offload their passengers to another vessel. He urged tour companies to study the entry limits to the island, which are designed to prevent damage to the marine environment.
He said a total of 1,203 people were booked to visit the Similan Islands during Wednesday's crush.
Meanwhile, the Department of National Parks, Wildlife and Plant Conservation is promoting Hong island as an alternative to Maya Bay, which has been closed indefinitely to allow for its ecosystem to recover.
Both the Hong and the Maya islands are in Krabi.
Hong island is under the supervision of the Tharn Boke Koranee national park. Weerasak Srisajjang, the park chief, said the island has natural attractions which are comparable to Maya Bay.
The island has take up to 1,950 visitors a day. Visitors arrive on the island in three groups of up to 650 people, one after another, throughout the day.
Currently, between 200 and 500 visitors come to the island every day. However, the number of visitors is expected to double during the high season, which starts from next month.
Mr Weerasak said major attractions include a lookout on the top of a hill on Hong island.
The island has been dubbed the "Green Island" for its cleanliness and the shallow coral reefs. A campaign has been mounted to ban the use of plastic and styrofoam containers on the island.