Mix all the marinade ingredients together and set aside.
Bring water to a boil and put in noodles, Stir noodles for 3-4 minutes until cooked . Drain the noodles in a colander and cool under running cold water, drain as much water off you can.
Mix cooked cooled noodles, green onions, cucumber, shrimp and crab meat in a bowl. Pour marinade over noodles. Mix well, cover and refrigerate allowing the flavors to combine (just an hour or two). Serve cold.