Combo question: urborg tomb of yawgmoth, torpor orb, kormus bell, dark depths = free Marit Lage?
It won't work.  Dark Depths' "Dark Depths enters the battlefield with ten ice counters on it." ability is not a triggered ability; you can tell because it doesn't use the words "when," "whenever," or "at," which are part of the definition of "triggered ability" in the Comprehensive Rules:


  112.3c Triggered abilities have a trigger condition and an effect. They are written as "[Trigger condition], [effect]," and include (and usually begin with) the word "when," "whenever," or "at." Whenever the trigger event occurs, the ability is put on the stack the next time a player would receive priority and stays there until it’s countered, it resolves, or it otherwise leaves the stack. See rule 603, "Handling Triggered Abilities."
  
  603.1. Triggered abilities have a trigger condition and an effect. They are written as "[Trigger condition], [effect]," and begin with the word "when," "whenever," or "at." They can also be expressed as "[When/Whenever/At] [trigger event], [effect]."


Instead, the ability is just a plain old static ability (specifically, a replacement ability, but that doesn't matter here).  Thus, Torpor Orb won't stop the ice counters from being placed on your Legendary Snow Creature Land — Swamp, and your combo won't work.

Stick with Vampire Hexmage.