Amazonas specialise in hanging hammocks, both free standing and ones that require clipping to trees. The name is very exotic sounding, but that really reflects where the range of Amazonas Hammocks are made.
Manufactured in Brazil in South America, Amazonas hammocks are available to enjoy in the UK via Garden Street, with free delivery. If you're after a swing seat hammock, try Glendale.
Just because you don't have two trees to hang the hammocks from doesn't mean that you can't enjoy a hammock! Many of the Amazonas Hammocks come with frames, to allow you to enjoy in open spaces. The Amazonas Atlas Hanging Hammock Stand can be used as an add on to enjoy your hammock on.
If you do have trees ready, or a frame ready, the Paridiso Hammock XL is a great choice, and available in a choice of four different colours.