Will my SCUBA equipment be affected by the altitude?

Yes, your equipment can be affected by altitude and you should be completely familiar with it before you go on an altitude dive.  A buoyancy check is critical as the air that gets trapped under your suit will expand at altitude, causing you to be more buoyant than usual.  In addition, sometimes gauges can behave differently at altitude so you really need to know how your gauges behave under normal circumstances.  If you have a dive computer, you need to know if you have to adjust it manually as some are self-adjusting.