OP said they want "trek" (a mountain)...no significant mountain in Siquijor Island. So, OP needs to scratch Siquijor....
@Calippo, why are you sooooo enamored with Siquijor? The fact is, OP wants to "trek" (a mountain).

OP said they want "trek" (a mountain)...no significant mountain in Siquijor Island. So, OP needs to scratch Siquijor....
@Calippo, why are you sooooo enamored with Siquijor? The fact is, OP wants to "trek" (a mountain).

I agree with the opinions of the others, Mt. Hibok2x would be your safest option for now. Unfortunately, Mt. Apo, Mt. Kitanglad and other mountains are off limits because of forest fires and the effects of El Niño.
I think that's what I said...

OP are flying in this weekend...It's summer time for crying out loud...there is NO typhoon. It's drought, El Nino...it's perfect at Camiguin this summer. They can also drop by at CDO for the WWR and Mapawa River Trekking...:)

they mention an interest in going to Siquijor, however in the limited time they have they can't do it.
as for being 'marooned' ferries can be cancelled at any time of the year, some times are more likely than at other times true, and now it's one of those times but it is never totally impossible and these days the coastguard are much quicker to cancel sailings than before. It's always good practice not to find yourself on an island needing to get to an airport right at the end, although this is worse for Siquijor than it is for Camiguin, as Siquijor doesn't have an airport at all.
as for getting a flight from Mambajao to Manila via Cebu that is not actually a bad idea, especially as the alternative, going via especially Laguindingan or Butuan is so much of a hassle by comparison. Very do-able same day too, as the flights to Cebu leave early in the morning, and it would not even be that expensive. Two people, especially if they booked ahead, could get to Manila for about 7,000-10,000. But you wouldn't want to be on Camiguin and needing to get a flight next day if the weather's turned and there's no ferries. The planes that serve the route are only small and in that situation, might easily be booked out.

Guys,
I'd like to thank you all for advice. I think we will catch a ferry to Camiguin. The island seems to have all we are looking for (vulcanos, waterfalls, hot springs, jungle trails, amazing coastline), it is a bit secluded and views are abolutely stunning as much as I can say looking at pictures on the web. The statement, that it has more vulcanos per squere km, than any other island in the world is also very appealing.
We have a flight home from Manila on Sunday evening, so we probably will get to Cebu on Friday (to have a bit of a buffer in case of unexpected) and fly to capital on Sunday morning.
Again, great thank you for all of you for finding time to provide me with your suggestion.
One last question before I start packing my bags: would you envisage any issues with ATMs serviced by european banks on Camiguin? Not in Mambajao obviously, but in other parts of the island...

OP, ATM machines in Camiguin almost always gets empty. They need more machines in there. To play safe, get some cash before going.

the Jagna-Camiguin ferry is only three times a week.
though there is better financial infrastructure on Bohol in Tagbilaran and Alona than there is on Camiguin, on these kind of short vacations, you may as well just cash up on arrival at the airport in Manila, enough money for the 2 weeks. The rates at the T1 airport are not that bad at all. Whatever you do, don't buy Filipine pesos in your home country. Wait until you get to the Philippines. If you are staying in a higher-end resort on Camiguin like Paras, they take int'l cards - but hardly anybody else does.
and also given your short timeframe, I don't see any benefit, if you are flying back to your home country on the Sunday, in flying from Camiguin to Cebu on the Friday. There is not a whole lot of appealing things to do in Cebu city for a tourist couple really. The Camiguin-Cebu flight is early morning. Go on the Saturday if there is a flight on that day (I think it is 6 a week) and you might want to consider spending your last night in Manila, not Cebu, and go directly from Camiguin to Manila in one day.
if you only have a 13-14 night vacation and your main interest is trekking and aquatic stuff, you really want to minimise how many nights you spend in cities as much as you can. If you can make it just one night in Manila at the end, the night before your departing flight, that would be a job well done.