Where was I - underground island?

[penlla]

I'm stuck on the underground island in the 'Where was I' comp. in the S.T. Help neded!!

[cheaton]

If you Google the river, you should get it!

[Old Timer]

penlla - I hope you have had more success with your googling of the river than I did!! I remain stumped.

[rozplants]

hasn't anyone got the answers this week?? must be the River Fleet but despite trawling (haha!) several sites & books I can't find the underground island..I'm sure like most puzzle/comp fiends I'd rather find out the answer thru doggedness but when it gets to a few hours before the deadline I get deperate! I've entered this comp most weeks for years & have never won despite (usually) getting the answer right...

[sir.prize]

It's not the Fleet.

Try another river . . . .