The 25-year-old, full of confidence after claiming 400m freestyle silver on Monday, enjoyed a race-long battle with Hungary’s reigning European champion Boglarka Kapas before getting the edge by two-tenths of a second in 8:16.17.
Gold went to outstanding American Katie Ledecky in a world-record time of 8:04.79 – she also beat Carlin to the 400m title in similar fashion.
After missing out on London 2012 through illness, Carlin – coached by Dave McNulty and Graeme Antwhistle at the British Swimming National Centre Bath – was thrilled with her achievements in Rio this week.
“If someone had told me four years ago that I would be stood on a podium twice with two silver medals I would have said there is no way,” she said.
“It has taken a lot of time to get here and there have been times when I haven’t believed in myself but my family and all of the support staff around me have believed in me.
“I feel very lucky to have gotten on the podium again. Since I was a young girl it has been a dream to go to an Olympics and to finally be here is a dream come true but to be on the podium twice with two silver medals definitely hasn’t sunk in, it feels a bit surreal.”
And there could be more medals on the final day of the Olympic swimming meet, with backstroke specialist Chris Walker-Hebborn part of a GB men’s 4x100m medley relay team that set the fastest time of 3:30.47 in qualifying on Friday.
That final is taking place at 3.04am BST, just after the women’s 4x100m medley relay featuring O’Connor – Britain were eighth-fastest qualifiers in Friday’s heats.
Picture by: David Davies / PA Wire/Press Association Images