Possible Clues:

• Mammoth
• A little bird starts to tell me how big it is
• Liner with strong man in charge
• Huge - disaster struck this ship
• It was a big loss to shipping
• With a little bird I can make it largely go down
• That's one big one that won't get off the bottom
• I can be under the little bird to make it very big, but that wouldn't stop it going down
• Of enormous size, like the stricken liner
• Of great size, like a sunken ship