Water dive and Benji
Ok so the premise is for Ethan to dive into the water tank and change the chip so that Benji could pass through the security without being picked up.
There's 3 min to achieve this before Ethan's oxygen runs out.
Ok all good so far.
What i don't understand is why this has to be at the same time.
Surely Ethan could of done his part first and swapped the chip then once successful Benji can do his part knowing the chip was changed and do his part with no added pressure?
It seems like they give themselves an unnecessary stress of achieving both at once, yes its good for the suspense of the film but why did Benji have to start at exactly at the same time as Ethan?