Does flying over water a low level affect the lidar/ obstacle avoidance sensors.
Iām going to say it depends.
Iāve never had issues but I have read (not sure where) that the water can act like a reflector and confuse downward looking sensors. I canāt see why it would affect obstacle avoidance around and above a drone though.
I guess the question is āhow low is low?ā.
The bigger issue I find, is the water I fly over is the sea and the few times Iāve flown low Iāve always tried to estimate the wave height and consider that as my zero level and then work up from that. If itās a pond, or protected lake with little water disruption then I have flown as low as 1or 2ft above it.
That comes more down to nerves and not hitting the stick to go down 
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If youāre flying the Neo, never ever ever fly over water, unless your CareRefresh is up-to date. So many people have had theirs fly off, never to return.
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Iād say that you need to be paying very close attention to what your drone is doing if you are low over water, and donāt trust the downward sensors or the height displayed on the screen. Did a bit of this back last autumn and found that it was very difficult to maintain station hovering over a river; the drone tended to be moved as if by the downstream current. I think the situation was probably exascerbated (stop that, you fool, youāll go blindā¦) by the banks affecting los to the gps satellits, with less satellites visible.
This was at about 2ā above the water, the intention being to get a shot of flying backwards low over the surface then out over a wier, which I managed fairly successfully. 2ā is plenty low enough for your prop downwash to ripple the water, in fact this seems to happend from about 12ā, and this circular rippling might have had an effect if the sensors āsawā the ripples as a target, which moved downstream with the current. Another consideration is that the water was quite clear, and the sensor might not have been seeing it alt all, in which case it should presumably have reacted to the river bed but it didnāt in any way I was aware of.
I would not try this over open sea, where I think a rule of thumb might be to keep high enough above than the wave tops to stay clear of spray; say 30ā even in calm conditions. You donāt want a corrosive salt-water mist getting inside your drone!.
And, as Binman says, donāt hit the stick to go down!
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I definitely wont be flying the neo over water especially now.
Like you say ive heard of a few drones disappearing over water and ive read a few posts about drones landing on water.
Ive no info on make/model etc so I thought Iād ask the question.
P.S. the neo has just arrived waiting to be registered along with care refresh.
Thanks for the replies folks. 
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Water can confuse the sensors. The sensors need to be able to distinguish things, itās hard to distinguish water from water. You can still do it, just donāt get too low. My mini 2 dont tend to like hovering within 5mtrs of water, it drifts and wanders all over the place. The Air 2 is a little better, but I still wont trust it within 5 mtrs of a clear surface.
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My drone manual says water and dark surfaces could cause the ground proximity not to work. So i guess see what the manaul says.
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Iām flying over the sea on a very regular basis, sometime as low as 5 feet depending on the sea conditions. I donāt seem to have a problem but the drone can behave a little erratic at times.
My footage this evening, again no issues whatsoever.
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Iām being overcautious, then. Youāre about 15ā above the surface there I reckon, and the screws are churning up a lot of spray, I would guess to within 10ā of you, but there were no Issues.
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Show us, show us, o you mite, Molesworth!
Cāmon, Johnster, itās about time you posted some images of some sort.
āTheJohnster? Post images?ā
Airdata for the flight will give you satellite counts, which might validate this conjecture. Also, āfewerā. 
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Did some searching on Google/DJI and found this.
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TBF Heās posted an image AND a location to Drone Scene.
Which reminds me I have a few places to add.
I would use the words of Mick Dundee āThatās not open seaā¦ ā but the couple of times Iāve flown off the coast thereās barely been any swell. 
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In that case, I offer my apologies for ragging on him. 
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No screws on those vessels, water jet unitsā¦ Average following speed around 28knots (32mph) at that point of its journey. You were correct, I was 15 feet above the water at that point.
I do however also give the drone a good clean afterwards in case theres any lingering sea water residue.
Do you often fly around the Solent? It may not be open sea as in the definition of but I can assure you itās no lake most of the time. I do also fly in conditions well over barely a swell, all part of the experience. 
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No need, mate, itās only bants, innitā¦
My local sea is the Bristol Channel, which can throw up some fairly lumpy sea conditions without needing a great deal of wind. Particularly with westerly winds against an ebb tide; the tidal currents are fierce and the result is a short but steep and high āchopā. My drone can handle level 5 winds, Beaufort Force 5 in other words, and this can easily produce unpredictable 7ā or 8ā waves close to shore around here, exactly where one would be flying a drone, particularly if an incoming wave meets backwash from where the previous one hit the cliffā¦
Conditions are a little more sheltered and Solent-like upstream from Lavernock Point, but, like the Solent, can be pretty lumpy just the same!
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How many have you crashed?
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Enough to know that you need to pay very close attention to what your drone is doing!
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I flew my mini4pro over a lot of ice, waterfalls, gorge rivers and open sea in Iceland recently - no issues but I chose a height for the shots and stuck to it. In the past, I did try to see if the drone would continue downwards but certainly
the mini 4 pro stopped descending when it got close (within a couple of feet)
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