How large could an aquatic humanoid get?
Vertebrates on land are limited in size by various factors. However, in the water, they can get much larger. How large could an aquatic humanoid creature (like cthulhu) realistically get, and what adaptations would be necessary for it to grow as large as possible? How would it sustain itself?
The only requirements are: 1. It is completely or partially humanoid in shape 2. It is as large as possible 3. It could realistically evolve on Earth