The Department of National Parks, Wildlife and Plant Conservation has announced safety measures will be imposed ahead of the reopening of the Tham Luang Cave site in July.
In 2018, the Tham Luang Cave flooded, trapping 12 young Wild Boars football players and their coach for 18 days before they were rescued. The news made international headlines.
Atthaphon Charoenchansa, director-general of the Marine and Coastal Resources Department, is visiting the Tham Luang-Khun Nam Nang Non National Park in Mae Sai district of Chiang Rai province to survey the area this weekend.
The visit is joined by Chaiwat Limlikhit-aksorn, director of National Park Office; Chutidech Kamonnachanut, director of the Conservation Area Administration Office 15 Chiang Rai; and Vernon Unsworth, a British cave diver who took part in the rescue mission.
Mr Atthaphon said an event marking five years since the Tham Luang Cave rescue will be held.
He said Tham Luang has become a tourist destination among international travellers, but the cave's interior is vulnerable and can be hard to navigate, which complicates sightseeing.
Therefore, measures will be imposed for people who want to explore the inside Tham Luang Cave. Currently, only an exhibition zone and the area in front of the cave is open to the public.
In July, the national park will allow an entrance to the first cave chamber, some 150-metres long, he said. Each tour group must consist of a maximum of 25 people and each round lasts 30 minutes.
The authorities only allow 16 rounds, or up to 400 tourists, to the chamber per day, he said.
He said for the second chamber, only four groups consisting of 15 people each can visit that chamber per day, he said, and they must submit an entry application at least one week in advance.
For the third, only researchers and experts will be allowed entry, he said, noting they must submit a letter to the department at least 30 days in advance.