The Spanish model and Australian soap star were eliminated from the reality contest after losing a bottom three skate-off with Hollyoaks favourite Jennifer Metcalfe, who was granted a reprieve by the public when voting lines reopened.
When speaking to hosts Phillip Schofield and Holly Willoughby, McLachlan thanked his professional partner Maria Filippov and joked that he was now looking forward to riding the waves Down Under.
"Well, the good news is there's a six-foot swell coming in at Bondi [Beach], but seriously I've had the best time with this bunch [of contestants] over here, and [Filippov] is an absolute treasure."
Rivas, meanwhile, came off the ice panting from her skate-off performance and stated only that she was "gutted" and "really sad" at her exit.
Her partner Lukasz Rozycki added: "She improved so much since the first time I saw her, I'm really really proud."
'Comedy' Dave Vitty, Sam Attwater, Dominic Cork, Chloe Madeley and Denise Welch - who were all granted safety by viewers earlier tonight - will join Metcalfe and last week's surviving six for the official beginning of the skating competition next week.
Dancing On Ice returns next Sunday at 6.35pm on ITV1.