Palau Jellyfish Lake permit: Rock Islands only, or add the lake?

Do I actually need the Jellyfish Lake permit, or is a Rock Islands day enough?

Palau visitor guidance lists the Rock Island permit at $50 and the Jellyfish Lake permit at $100, both valid for 5 days and available through Koror State Ranger office or authorized tour companies. (Pristine Paradise Palau traveler tips)

Koror State says visitors need a Rock Island Use or Jellyfish Lake permit for the area; Jellyfish Lake itself requires the Jellyfish Lake Permit, and fishing requires another permit. (Koror State Rock Islands Southern Lagoon fact sheet)

Koror State tourist information says Palau has more than 50 marine lakes and Jellyfish Lake is the only one open to visitors. (Koror State Government tourist information)

Are the jellyfish currently present enough to make the lake worth planning around?

CRRF reports the current average 0-12m water temperature as 31.4°C / 88.5°F and the ENSO phase as Neutral. (Coral Reef Research Foundation Jellyfish Lake conditions)

CRRF says its next-three-month forecast is a guide, not an absolute truth, and asks visitors and guides to report unusual conditions. (Coral Reef Research Foundation Jellyfish Lake conditions)

Should I book a standard boat day, or pay for more route control?

Koror State says visitors may use designated tourist activity areas, while other land is reserved for Palauans and local residents. (Koror State Rock Islands Southern Lagoon fact sheet)

Koror State places Jellyfish Lake on Mecherchar and says it is about a 45-minute boat ride from downtown Koror. (Koror State Government tourist information)

UNESCO describes the Rock Islands Southern Lagoon as a 100,200 ha property with 445 limestone islands and 52 marine lakes. (UNESCO Rock Islands Southern Lagoon)

What can I safely do in the lake, and what should I avoid?

Koror State says there is no SCUBA diving in Jellyfish Lake because the lower layer has no oxygen and contains poisonous dissolved hydrogen sulfide. (Koror State Government tourist information)

Koror State says large animal life in Jellyfish Lake is limited to the top 15m, with a bacterial layer around 13-15m. (Koror State Government tourist information)

How much room do I need around hotel pickup, weather changes, and the trip back to Koror?

Palau visitor guidance says the Rock Island and Jellyfish Lake permits are valid for 5 days and can be obtained at the Koror State Ranger office or through authorized tour companies. (Pristine Paradise Palau traveler tips)