This is the 14743rd most frequent Polish word.
płetwonurkowie
"Scuba divers."
Plural and subject of the sentence, indicating the people performing the action of exploring underwater caves.
Płetwonurkowie odkrywają tajemnice podwodnych jaskiń.
The scuba divers are discovering the mysteries of underwater caves.
Plural and objects of the observation in the sentence, indicating those who are entering the water.
Widziałem płetwonurków wchodzących do wody.
I saw the scuba divers entering the water.
Plural and indirect subject of the sentence, indicating the participants of an educational course.