I just bought the novelization hoping it makes the Nibiru mission make sense. It is really the only part of the film that I can't make work in my head.
Bob Orci did explain that on Trekmovie, but it's still open to question. The volcano interfered with their transporter lock unless it was line of sight. Apparently between motion and natural disasters, this timeline's transporters are quite finicky.
Also I gathered from Spock's line "that the planet will die" meant the small groups of inhabitants were all near the volcano, not that the planet itself would be destroyed.
To me the bigger question is, if they were so worried about the Enterprise being seen by the natives, why did they park it underwater in the FIRST place-- and so freakin close to their temple??
Have they never heard of "standard orbit" in this universe?
They never really explained why they had to bring the Enterprise down to the planet. Was the volcano's ash screwing up the atmosphere so no transporter activity could take place between orbit and the surface? It looked like Kirk and McCoy were going to use the shuttle to escape in as well. It was still cool to see the Enterprise rise out of the water. Very Space Battleship Yamato.
The diving suits reminded me of TMP uniforms, I guess it was their color.