The Threat from the Sea Series by Mel Odom

In the first book of a sweeping new "Forgotten Realms" series, an evil warlord from the depths of the Trackless Sea rallies the undersea races of Toril in a surprise attack on the Sword Coast. This novel shares a setting with the "Sea of Fallen Stars" adventure boxed set.

The sea war rages up and down the Sword Coast, leaving the busy harbor of Baldur's Gate in flames. Following his mad quest, the evil Iakhovas has found a gateway into the protected waters of the Sea of Fallen Stars, and now no coast is safe from his marauding armies of the deep.

The exciting conclusion to the Threat from the Sea. Iakhovas has been the cause of more destruction than any force since the Time of Troubles, and his true objective has been a mystery . . . until now. When a young sailor's journey is complete, and an aging bard's final song is sung, an explosive climax sets all of Faer n reeling