Suspicious Bubbles are a feature found in the Shipwrecked DLC in the Medium or Deep Ocean Biome. They are similar in function to the Suspicious Dirt Pile of regular Don't Starve. They can be investigated which will reveal a trail leading to a Whale.
Upon investigating the bubbles, a line of small bubbles will "pop" at the surface of the water in a particular direction, leading towards the next set of Suspicious Bubbles. After 6 to 12 Suspicious Bubbles are successfully investigated, the character will alert the player that the creature is close and a Whale will be found in the indicated direction, rather than another bubble. If the Suspicious Bubbles are not investigated in time, they will disappear. However, new Suspicious Bubbles can be encountered later to start a new hunt. Suspicious Bubble trails lead to a Blue Whale most of the time, and a hostile White Whale the remainder of the time. The chance of finding a White Whale instead of a Blue Whale starts at 5% and increases over time to 33%.