The last public appearance of the Council of Tides was twenty-five years prior to the events of Crooked Kingdom. The Tides protested the proposed destruction of one of their watchtowers, and when the vote was not in their favor, they destroyed the Stadhall with a huge wave.
The Council of Tides allegedly appeared to stop the auction of Kuwei Yul-Bo's indenture, claiming the auction was compromised. However, that was actually the work of a group of Grisha refugees in disguise, only four of whom were Tidemakers, acting according to Kaz Brekker's plan.
The real Council of Tides accosts Kaz three weeks later and ask him for the location of Kuwei Yul-Bo, fearing the danger they would face if the secret of jurda parem became known worldwide. Kaz continues to claim that Kuwei is dead; the Tides first threaten to destroy his shipments and Fifth Harbor, then begin to drown Kaz. Kaz threatens to start plagues at their watchtowers, which would cause the city to force the Tides to register their identities or burn down the towers. The Tides leave Kaz, but not before issuing another threat.
The Council of Tides man the Tidemaker watchtowers day and night, monitoring the harbors. The towers are thick obelisks of black stone located at various points along Ketterdam's coast and its small outlying islands. The Council of Tides controls the tide and with it, who can come in or out of the city by ship. They also keep the tides permanently high over the land bridge that otherwise would connect Kerch to Shu Han.
The identities of the Council of Tides remain hidden. Not even Kaz Brekker was able to learn their identities, where they lived, or how their loyalty to Kerch had been guaranteed. When they appear in public, they are shrouded in thick mist and wear blue hooded cloaks that move without a breeze. They wear masks that give the impression of looking into a starry night sky.