Here are season 4 episodes 7 and 8 previews as shown by TV Guide. Not much of a spoiler but I was instructed to past them here rather under the thread for the just screen episode.
The three remaining teams scramble for a long-term advantage. One pair runs themselves ragged with an elaborate shelter build, while another hazards the freezing Pacific waters on their own small craft.
Existential threats are faced at every turn by the three remaining teams after nearly a month on the island, as one participant is forced to fight a raging fire, while rising tensions could end a partnership.