Whitehaven head coach Don Gailer described winning promotion to the Championship, with a 60-12 home victory against Gateshead, as a "relief".
Gailer's side needed just a point to secure the fourth and final promotion place and join Cumbrian rivals Barrow and Workington in the second tier.
"Promotion was the stated goal by the club," Gailer told BBC Radio Cumbria.
"There's a sense of relief that we've done it today all round, and we did it in style. The boys played well."
Haven scored 11 tries in the success, with a hat-trick for wing Craig Calvert and braces for second row Richard Varkulis and centre Jessie Joe Parker.
Also among the tries were Paul Cullnean, Tom Hemingway, Lee Doran and Carl Rudd, who also added eight conversions to the Marras tally.
"It was great, the forwards laid the platform and the half-backs [Jamie] Rooney and Rudd got us attacking," Gailer added.
"When Rooney got a bump to the knee we weren't going to risk that and put Tom back to half, but Rudd took over the show.
"He was outstanding today."