Below is a walkthrough for the In the Belly is a Beast side quest in Tiny Tina’s Wonderlands. To obtain this quest, speak with Otto in Crackmast Cove.
Collect 4 puppet limbs
Follow Otto a short way until he stops at a log. Kill the crabs then retrieve the Puppet Arm. Deliver the arm to Otto when he requests it. Follow him a short ways again until he stops by some strangers. Defeat Captain Hill and his crew then retrieve the leg and give it to Otto. Afterwards, follow Otto again. When he stops, retrieve the leg on the ground and give it to Otto. Follow Otto yet again. After his speech, defeat the crabs then grab the puppet torso and give it to Otto.
Enter Whale’s Belly
Head on in the whale’s mouth then defeat the crabs inside.
Find Otto
Approach Otto a short ways ahead. Listen to Viscetta.
Kill Viscetta
Defeat her.
Take puppet head
Grab the head then put the head on the body.
Listen to Nico
Hear Nico out.
Exit whale
Head on out to complete the quest.