( ( ( ( ( Usually ( ( ( the purpose ) ( of ( a ( scuba ( diving ( or ( snorkeling excursion ) ) ) ) ) ) ) ( is ( to ( observe ( ( ( protists ( -LRB- ( i.e. ( , ( macroalgae -RRB- ) ) ) ) ) and ) ( animals ( within ( their ( underwater habitat ) ) ) ) ) ) ) ) ) ) , ) but ) ( divers ( often ( ( ( ( hunt and ) collect ) ( in addition ) ) ( to observing ) ) ) ) ) . )
(ROOT (S (S (ADVP (RB Usually)) (NP (NP (DT the) (NN purpose)) (PP (IN of) (NP (DT a) (NN scuba) (NN diving) (CC or) (NN snorkeling) (NN excursion)))) (VP (VBZ is) (S (VP (TO to) (VP (VB observe) (NP (NP (NNS protists)) (PRN (-LRB- -LRB-) (FW i.e.) (, ,) (ADJP (JJ macroalgae)) (-RRB- -RRB-)) (CC and) (NP (NP (NNS animals)) (PP (IN within) (NP (PRP$ their) (JJ underwater) (NN habitat)))))))))) (, ,) (CC but) (S (NP (NNS divers)) (ADVP (RB often)) (VP (VB hunt) (CC and) (VB collect) (PP (IN in) (NP (NN addition))) (PP (TO to) (NP (NNP observing))))) (. .)))
Usually the purpose of a scuba diving or snorkeling excursion is to observe protists (i.e., macroalgae) and animals within their underwater habitat, but divers often hunt and collect in addition to observing.
(ROOT (S (NP (JJ Multiple) (NN fission)) (VP (VBZ is) (ADVP (RBR more) (RB often)) (VP (VBN observed) (PP (IN among) (NP (NNS protists))))) (. .)))