Cistern - Jump through the Level?

[in these arms]

I'me just roaming through my TR collection. And I decided to have a go at Cistern, and while playing, I've noticed you don't need to open the second door on your left as you enter the Cistern.

(The furthest away) But you need to do the first one (with 2 gorillas and Pierre)

Anyone else notice this?

[shaahinkaaveh]

I remember having done something strange which made the level oddly easier. I remember I didn't need to do some job before and some job after flooding the area (that is, I simply flooded it as I entered). But what that was and how I did that, can't remember. :o

[Laraman]

Actually you do need to do the door. If you flood the cistern you swim past the spikes and collect the gold key. It's used just after you use the two silver keys.