Tideless Deep is the 8th province (Stage 1 Province 8) of the Oceanic Future, accessible (along with Rough Expanse and Serene Waves) after taking control of Strong Tide to the southeast. Taking over Tideless Deep unlocks Glimmering Surf.
If previous sectors acquired by negotiation:
How can I help you, mate?
If at least one sector taken by force:
Do I have to draw another card to find your way home?
Can you float? If not, you should start learning.