Make no mistake about it... you can shoot the 60mm day in, day out in Lembeh and be happy. HOWEVER, I am a HUGE fan of the 30mm and think you should strongly consider it. I shoot an EM1 in Nauticam, so I'm not sure about your port setup for your Oly housing (but would assume that you'll need a new one for the 30mm). I bought the 30mm and associated port prior to my first and only trip to Lembeh for the Alex Mustard workshop in Oct 2018. I had used the lens/housing for one photo trip prior to Lembeh. There was a great write-up on the lens in the bi-monthly Underwater Photography magazine that pushed me to purchase the lens.
In reviewing my image metadata for the trip, I took 2525 photos in Lembeh. 2313 were with the 30mm, 212 were with the 60mm. I never would have expected this before the trip. I had assumed I would have used the 60mm all the time, with the 30mm here and there for variety. The fact of the matter is, many of my photos could have been taken with either lens, but the 30mm worked for much of what I was shooting. You'll be seeing plenty of bigger subjects that would do better with a 30mm (larger frogfish, mandarin fish couples mating, scorpionfish, etc etc etc). Additionally, you can still use a wet diopter with your 30mm (despite what the UwP write up says about the difficulty of doing so). You'll have a paper thin depth of focus, but with proper techniques like thumb-focus rocking and using a small aperture, you'll be just fine and will come up some very different shots. And that to me is the key with having that second lens... I found that the 30mm just gave my photos a different feel than the 60mm. You'll see many of the same creatures over and over again during that week. Between my 30mm with/without wet diopter and 60mm with/without, I felt like I had four different opportunities with subjects to capture different styles of images. The 30mm can focus SUPER close... essentially on the glass of your port, so you will be able to get much closer than the 60mm to non-skittish subjects like nudis. You'll have to get creative with strobe positioning with these tight shots.
Here are a few sample images I shot in Lembeh with the 30mm.
When do you leave for your trip? Lembeh was amazing. I wish it wasn't on the other side of the world... it was about 36 hours door to door for me. I hope to get back some day.



