water

• In over your head

  To be involved in a situation or task that is too difficult, complex, or overwhelming for you to manage.

• The floodgates opened

  A sudden, overwhelming release or outpouring of something, often emotions, information, or events, after a period of being held back.

• Open the floodgates

  To allow a large number of things to happen or be released suddenly and uncontrollably.

• Placid as a millpond

  Extremely calm, tranquil, or undisturbed, often referring to a body of water or a person's demeanor.