A while back, Kerry Clare asked in the comments how the lightbulbs in the flood-like lights towering above indoor pools are changed, and ever since I haven't been able to stop wondering (Yes, breastfeeding at 4am is a perfect time to obsess over those damn light bulbs, thanks for asking!)
So I finally asked a lifeguard! And he knew! And then I followed up with my all-knowing pool/swimming source, Coach Dave...
Cherry pickers, scissor lifts and/or "zoom booms" (telescopic forklift-y things).
They bring them in from outside and drive them on the deck (how this happens, I'm not sure, but apparently much of this equipment is max. 6 feet wide, so maybe they get in through double doors?)
AND, they have to close the pool, and sometimes even drain it, for fear of falling/broken glass!
Tada! Mystery solved!