Of all the creatures so far I hate fighting these things on land, boat or in the water.

They always stay just out of range and whenever you are about to shoot one or attack it another hits you from behind. However my pet hate is when they circle up in the air, usually just the last one and you can't break out of combat.

Anyone have a strategy they have successfully used????

Yeah that's fine when they come in range and IGNI works just as well. My frustration is when they stay out of range mor than the actual tactic to hit the bloody things :-)

on the water just dive, they will dive as well and then you can easily shoot them. On land just use the short crossbow shot to floor them

Thanks I did notice diving was a good way to avoid them just need to be more skilled at shooting the bloody things as well!!!!

They are easy actually if you stick with the correct tactics.
Wait until it attacks you from the air and block\counter attack it. Whether you will kill it with your counter attack or you will one hit it while it's lying on the ground with your power hit. You can actually kill infinite numbers of these creatures like that without being hit a single time.

correction; Drowners are by far the most annoying creature ever concieved

Most аnnoying creature EVER is cliffracers.

As for Ekhidnas - crossbow / aard/ igni - falling - sword hit - finish.

Why? underwater you can just one hit them with the crossbow and it autoaims.

the most annoying creatures are the spectres.

by the way ekhidna decotions are really good.

Have you invested in the "Far-Reaching Aard" enhancement? Having played as a Sign specialist, I've rarely had issues with ekhidnas.

They made my first hour of gameplay the most difficult of my life (playing on death march) :)

On my opinion, most annoing creatures in game are stools and chairs and crates. Geralt become just fish in the net.

I rarely use AARd but that makes sense.
ABSOLUTELY True!!!!! ;-)

Hornwall. Use it, walk up to the downed Ekhidna/Siren, finish it off. if there is another nearby kill that one too. Then reuse Hornwall and repeat.

Having enough armour that they only do minor damage helps...

You can also just time an attack "just right" and swat them out of the sky with your sword, or use Aard or Igni... but those are very short ranged and only deal with one at a time... Hornwall gets them all.

Sirens and their ilk become less trouble than Harpies and Erynia once you've recovered it. (It was lost on Undvick).