If a heavy truck crashes and plunges into deep water (rivers, lakes, or canals), what is the correct cab escape technique?

1. Unbuckle seatbelt immediately, wait until water fills the cab to equalize internal and external water pressure, then push the door open or break a side window with an emergency hammer to swim to the surface
2. Try to force the cab door open immediately while the truck is floating on the surface with high outside water pressure
3. Remain seated with windows tightly closed and wait for professional salvage divers to arrive hours later
4. Drink the water inside the cab to delay water level rise