The distance from where the crew is trapped to the main entrance is about a half a mile, and the boys had to travel most of that distance underwater to reach freedom.
The Thai soccer team ventured into the Tham Luang cave complex after practice and became trapped by rising waters more than a fortnight ago. One diver, a retired Thai Navy SEAL named Saman Kunan, died in the rescue effort last week.
"Hooyah", the Thai Navy SEALs, who have played a crucial role in the against-the-odds operation, said in a Facebookpost as they announced that a total of 8 members of the "Wild Boars" football team had been rescued on Sunday and Monday.
The latest rescue operation began at about 10.08am local time (1.08pm AEST).
Because of the heavy rains, which eventually eased in the afternoon, Narongsak said the decision had been taken to "not to waste time ... for the third planned mission".
Nargonsak said this phase may take longer than the previous two rescue missions, which took up to 11 hours.
"All eight rescued boys today are in good health, none have a fever", Jesada Chokedamrongsuk, permanent secretary of the ministry of public health, told a news conference in Chiang Rai in northern Thailand.
However the boys will remain in quarantine until doctors were sure they had not contracted any infections from inside the cave. They did get a treat, however: bread with chocolate spread that they'd requested. The complex and unsafe effort to rescue them has gripped the attention of much of the world.
As the minutes stretched into hours under the hot sun in this corner of north-western Thailand bordering Myanmar, hopes were rising that news of a third successful rescue by the so-called "all-star" team of Thai and global divers - which included as many as eight Australians in support roles - was imminent.
Two are being treated for a "minor" lung infection.
Thai cave rescue sees four more boys freed The four were the first of the 13 Mu Pa team members who were evacuated from the cave since they became trapped on June 23. The eight boys who've been rescued so far have all swum out of the cave, each escorted by two expert divers.
He said, "the kids are footballers so they have high immune systems". "Everyone is in high spirits and are happy to get out. We are just praying for them to have a safe return".
It could be at least seven days before they can be released from hospital, Jesada told a news conference.
It was clear doctors were taking a cautious approach.
Still, health officials were wary of possible infections "because we have never experienced this kind of issue from a deep cave".
The first 4 boys who were rescued the other day, aged between 12 and 16, are now allowed to eat normal food once again.
At least nine ambulances and a convoy of other vehicles were at the cave site Tuesday.
That left two boys and their 25-year-old coach still inside the cave but authorities were confident of getting them all out by Tuesday evening via a claustrophobic network of tunnels that in some places were completely filled with water.
But Governor Narongsak Osottanakorn, who is coordinating efforts to save the boys, said the machine is "not practical for this mission".
Mr Musk on Tuesday visited the cave and posted pictures and videos online.
Despite being turned away, Musk put out an optimistic tweet saying he was 'leaving [the submarine] here in case it may be useful in the future'.