In reply to The New NickB:
I swim a lot in the sea, and 400m off is a LONG way. You would probably have been swimming out to sea for about 7 minutes, or used a current to go out that far. That far out the protocol is for lifeguards to be calling for coastguard assistance in any rescue they may be doing, meaning lifeboat or chopper even if they have their own Surf rescue boat or jet ski. To be honest there is not usually any need to swim that far out, and even swimming 200m out feels very far indeed. A lot can happen in that 7 minutes getting back in. On most coasts 100-150 m will get you out the back beyond the break, but there are a few places where it won't. Either don't swim at those, or use the surf and do ins and outs. Very tiring and good workout in itself.
I usually take my rescue tube when swimming a long way at sea, or I'll have a handy board paddler with me. The tube is good, as it is high vis and if needs be I can hold onto it, or use it on someone else, yet you don't notice it when you are swimming especially.
My friends have the chill swim tow float.
https://shopdesq.imgstg.com/index.cfm?fuseaction=main&OrgID=20431
Useful, but not a rescue device...
They stick their cameras and thermometers on waist belts, but I shove mine in the top of my wetsuit.... Or give it to the board paddler.
Tube...
http://www.childsplaysurf.co.uk/index.php?route=product/product&path=60...
Board...
http://www.surfprodesigns.com/index.asp-Q-Page-E-rescue-boards
I had a non chip key cut for the car, that stays in there... It won't start the engine, but will get me in and out... The actual car key stays in the car.... I do have a dry bag for a phone, but don't trust it very much, as the radio ones we have at work leak as soon as you hit any surf...
Enjoy and if you do like it enough, consider doing a lifesaver or lifeguard qualification with either slsgb or rlss to bolster your confidence in dealing with situations.