Complex sentence: Sunken Meadow State Park began as a bunch of parcels of land own by the town of Smithtown that were brought together in bunches and when the park first opened in 1928, it was large.
Split into simpler sentences: Sunken Meadow State Park began as several parcels of land owned by the town of Smithtown that were combined to form the park. When the park first opened in 1928, it was large.