“Its Hywind turbine, mounted on a ballasted vertical steel cylinder that floats upright and is anchored to the seabed, has a unique navigation system developed by Statoil to keep it in the position.” (http://uk.reuters.com/article/2015/07/07/us-statoil-windpower-floating-idUKKCN0PH1ST20150707)
That would be the anchor.
Australia’s federal environment minister “has already approved a plan to dredge 3m cubic metres, equivalent to 5m tonnes, of seabed in order to expand [Queensland’s] Abbot Point for an increase in coal exports. A proposal to dump the sediment within the [Great Barrier] reef’s marine park has also been approved.” (http://www.theguardian.com/environment/2014/sep/02/abbot-point-port-developers-ditch-great-barrier-reef-dumping)
The world’s first coal reef.