Somewhere in the hinterlands of Nigeria right now - and at any other given time, really, there's someone planning to visit Lagos for the first time. Maybe even move out here for good. This city is easily the destination of choice for many Nigerians embroiled in the pursuit of happiness. About 18 million people currently live here and that number is sure to keep swelling over time.
I mean, look at this awesomeness:

And this:

Yep, that's Lagos, alright. Who wouldn't want a piece of that when most of the other cities look like a barren wasteland in comparison?
So, say you moved out here, courtesy of a new job or you managed to browbeat some relative/friend of yours to allow you stay with them before you get something going for yourself. Sooner or later, you're going to be scouting for an apartment in the city. Whether you get an agent's number or you get to check out apartments on a listing site, one thing you have to consider is this:
"Lagos is a different city when it's rainy season."
...Unless, of course, you're in Makoko. Same scenery out there all year. No surprises.
When it rains in Lagos (and boy, does it rain alot), the ambiance is different. The beauty usually fades into the flood and only returns when they recede. In many parts of the city, roads turn into streams - and not the clean free-flowing type. Unless you have scuba gear or a jeep (if the flood isn't too high), you will be trapped indoors. And it is almost irrelevant whether you're in the bourgeoisie "Island" part of town or in the "Mainland".
Make sure to check out the street beforehand
Or you may want to consider taking the ferry out of your street to get to work till the rains stop:

So, while making plans to move into a new apartment, you have to do right by yourself by going to the neighbourhood during rainy season to get a feel of the area. Check that the street is tarred and that the drains work - if there are drains.
You walk into a street like this, you have to check if those drains work (and why the lady has concern written all over her face. Might be apprehension for the impending flood)
Another tip:
Always take an apartment above sea-level, if you can.
Somehow, the landlord and the agent might conveniently forget to mention that the reason the ground floor apartment is cheaper than those upstairs is because of you very likely won't be enjoying it for the 6 months of rainy season anyway. When in doubt, just go up. You'll save your property and your sanity.

You have to be diligent with this stuff. Housing is expensive in Lagos and you don't want to get to feel like you were conned into moving into an apartment in a neighbourhood plagued by flooding. Do your scouting in the rain.
By the way, if all of this is music to your ears and you really want to channel your inner Ijaw by seeking to live around water all year, then, by all means, do it well. Go to Makoko. You'll feel right at home.
Just look at their floating school. Awesome stuff!