The Sea II reunites the quartet that Norwegian pianist Ketil Bjørnstad had assembled for The Sea, with David Darling on cello, Terje Rypdal on guitar and Jon Christensen on drums. Released by ECM in February 1998, it continues the cycle of water-themed albums that Bjørnstad began with Water Stories and carried on with The Sea and The River. ECM described the series as a musical roman-fleuve.

The label notes that studio work and touring in the years since the first Sea had sharply defined each player's task in the band. The session took place in December 1996 at Rainbow Studio in Oslo, with Jan Erik Kongshaug engineering and Manfred Eicher producing. Bjørnstad wrote nine of the ten pieces, and the tenth, Consequences, is credited to all four musicians. The theme was close to home. Bjørnstad had left Oslo for a small island to the southwest of the capital, where he lived for fifteen years.

He has explained the sea of the title as two kinds of movement in the music. One is horizontal, the linear motion of the waves, the other vertical, like seeing to the seabed on a clear day, which he called "total transparency". According to ECM, improvisation in this band is less about interaction in the usual jazz sense than about cross-currents. The album opens with cello and piano on Laila, and Rypdal's guitar enters with Outward Bound. Song For A Planet, Agnes and December are given largely to the piano and cello pairing, Mime belongs to Rypdal, and South is built on Christensen's drumming.

In Jazz Journal, Michael Tucker heard "quintessential ECM tone poem music", with Darling's cello "striking a typically meditative note" and passages "of extraordinary, soaring intensity from Rypdal". He also noted Christensen's way of floating across the barlines. Writing for AllMusic, Scott Yanow was cooler about the slow pacing, though he singled out "a few fiery and rockish solos from guitarist Rypdal". Tyran Grillo, on ECM Reviews in 2012, heard a darker descent than on the first Sea, with the drums as the only reminder of land.

CD, ECM 1633, first released on 23 February 1998.