So i've an Aquaterra and I believe a small pin has come off the clasp. I'm not sure what to call it though, and that's my question - what do i search for to get a new one?
When I put my strap on it used to click twice - once on one side of the clasp and then the final locking click.
Now however that initial click does not occur and it's quite difficult to put on as the strap extension flops around.
I've circled it in red below, and added some other details if someone could tell me what this is specifically called?

Apologies for something that maybe obvious.

 

Pins like that are often called "rivet pins". These are basically a stainless steel tube, open at both ends, and two small "rivet like" plugs, one driven into each end of the tube.

As to your other question about closing the buckle, I think we need to see a picture of the entire buckle in more of a general view.

 

Hy,
I think what you are missing is a spring that is inside that tube + small steel ball that is on the top (that small ball is where you circle in red) .

First click you dont hear now is where that ball slips in its place.

 

I do not know how this sistem is called but I think it will not be repairable (i think its integrated) and you will need whole new clasp.

 

Correct on what is missing. The ball and springs are not available separately. You can order the "underpiece" of the clasp separately, but getting the entire clasp would be easier than trying to disassemble the clasp and install the cover on the new underpiece.

 

Thanks guys.. shame about a new clasp. . that's alot of cash for a little ball. Ohh well

Here's pic of the clasp but think yous have nailed it.