Complex sentence: Indian naval divers on Wednesday afternoon opened the main hatchway of the stricken vessel, but visibility for the divers within the sunken boat was almost zero, and the effort to rescue or recover the 18 missing crew members was expected to take time.
Split into simpler sentences: Indian naval divers on Wednesday afternoon opened the main hatchway of a stricken. But visibility for the divers within the sunken boat was almost zero, and the effort to rescue or recover the 18 missing crew members was expected to take time.