The smell is not really so bad as you might think, especially not in storm drains, and even in sewers you very quickly become accustomed to it. It's more of a very old musty damp laundry smell than rancid lavatories . . so long as you don't go kicking up any pools of standing water.
The real concern is when you're in an enclosed environment with little to no airflow and the gas monitor goes off! That's a very real concern is that.
The type of images I usually take, similarly to a lot of other drain explorers, really don't paint an accurate picture of the environment. You know? They look serene, a little bit other worldly, with silky smooth waters and shiny textured surfaces. Of course it can look like that when you're down there, sans the silky waters. What you don't see in the photos are the huge fissured golden turds floating by, the blood stained panty liners wrapped around the ladder you're trying to use, the condoms clinging to your tripod legs, the hunking great clods of loo roll, the red nosed tampax swollen to the size of small rats floating along with their cotton tails all a tangle, the poop pebble dashing where a side pipe has ejected toilet matter at great speed on to the opposing wall, and the pools of fermenting cottage cheese fecullence. Then there's the sounds, the constant white noise of flowing water, traffic duf-dufing over manholes sending mad echoes bouncing in all directions, muffled police sirens, the sudden crashing roar of water as a lurid green torrent belches forth from a side pipe and collides with bricks and mortar.
It's fair to say that it's a bit of an assault on the senses on first venture into a sewer.
I can only say that if you're seriously considering, PLEASE find someone with some experience to go along with.
