The Terrors of the Deep narrative arc is comprised of three Nyrond and Her Environs / The Splintered Sun Meta-Regional "crossover" adventures, played in seasons six and seven. The narrative plot of the modules forms a continuous story bridging both regions.
The final module is published in two (minor) variations - the versions are virtually identical.
ESA6-04/NMR6-05 Gift of the Tempest
NMR7-02/ESA7-03 The Wake of the Tempest
NMR7-06 Eye of the Tempest
ESA7-06/NMR7-06 Eye of the Tempest
Note the module product codes are here given exactly as they occur on the published module covers.