Complex sentence: They reported seeing creatures swimming in the water--and one on a beach--with pink skin and spikes along their heads, estimated to be about 150 centimeters tall, with limbs and faces similar to that of a human but a mouth like a carp.
Split into simpler sentences: They reported seeing creatures swimming in the water--and one sighting on the beach--which had pink skin and spikes along their head. These creatures reportedly were about 150 centimeters tall and had limbs and faces that were similar to that of a human but a mouth like a carp.