What is the independent clause of dependent clause?

I want to explain my problems with the following sentences:

"Even boldly going where few have gone doesn't always lead to radical

conclusions. Over the years, researchers have set up
weather-monitoring stations in remote areas of Antarctica. According
to data from stations on the Ross Ice Shelf -where almost all
those taking part in Robert Scott's ill-fated South Pole expedition
perished sometime between late February and mid-March of 1912 -
temperatures as low as those recorded in Scott's journal have been
documented only once in the past 15 years."

1) In "where almost all those ......", who does those refer to?

2) That same clause started with where. What place does this dependent clause refer to?

3) What is the independent clause for this dependent clause?