Then they left, they left for the mountain, they went on up.
( ( Then ( they ( ( left , ) ( they ( left ( for ( the mountain ) ) ) ) ) ) ) ( , ( they ( ( went ( on up ) ) . ) ) ) )
(ROOT (S (S (ADVP (RB Then)) (NP (PRP they)) (VP (VBD left) (, ,) (S (NP (PRP they)) (VP (VBN left) (PP (IN for) (NP (DT the) (NN mountain))))))) (, ,) (NP (PRP they)) (VP (VBD went) (ADVP (RB on) (RB up))) (. .)))
They have no idea how far up they will have to go. 
( They ( ( have ( ( no idea ) ( how ( ( far up ) ( they ( will ( have ( to go ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP have) (NP (NP (DT no) (NN idea)) (SBAR (WHADVP (WRB how)) (S (ADVP (RB far) (RB up)) (NP (PRP they)) (VP (MD will) (VP (VB have) (S (VP (TO to) (VP (VB go)))))))))) (. .)))