This might just be me but the aquatic updates mystery items like the heart of the sea and that are intriging me. I have a theory and want to know others thoughts on this idea.
There once used to be a dimensional mod called the eternal frost which acted as an inverse nether.
The blue ice. Or ice obsidian could maby be like obsidian for a normal portal. The heart of the sea acts likes its lighter or key. They look like enderpearls. And ths shell and stuff could be from some unknown creature coming still. Also the new snapshot mentions words for the new light block words like (were are we. What is this)
Or mabey a new boss relating to this.
Not entirly sure but looks promissing.

UPDATE. Looks like my assumption has mostly been disproven as of the heart and shells make the conduit.