My Experience with cancellation/fees in my personal life
On occasion, I've had to cancel rather late for events or other arrangements, some I knew were full or high demand, and the vendor would lose out on that projected profit needed to cover costs, or guides, or equipment setup, or time took to arrange logistics, or the space for that person. Usually, there were fees associated with those cancellations. My wife would call to cancel and be notably embarrassed, remorseful, apologetic AND pay the fee. 

My Philosophy on cancellation - Why they exist
My wife would sometimes tell me about how awful she felt later (that we had to cancel).

I would ask her, "Did we pay the proper cancellation fee they had previously disclosed and asked for?"
She would always reply, "Yes."
Then I would say, "Then don't feel badly. If that business did their due diligence and set their cancellation fees properly to cover their financial risks for various trips, there should be no hard feelings. Now, if we cancelled late, and refused to pay the fee, then they have a right to feel angry."

My Promise if and when divers cancel an event
To conclude, when there is a deposit and cancellation timeline for an event, it's for a calculated reason. In those events, if you cancel relatively late in the timeline where a fee is required, I promise not to be upset by even the latest cancellations, as long as the diver is OK with the cancellation fee to be paid in the timeline as described.

 

Weather 
Rain alone is never a reason to cancel a dive. If a dive is cancelled due to weather conditions such as excessive wind, waves, current, or typhoon, we will announce the event cancellation as early as possible and any deposit paid will be refunded in the event that an alternate dive site/event cannot be arranged. In the case of island trips, we often have to make cancellation decisions about weather predictions well in advance of our departure. For a ferry departing Friday evening, I try to make the final decision by Thursday evening or Friday early in the morning. Those are tough calls to make, but we err on the side of safety and diver satisfaction. 

Deposits and Cancellations 
All weekend dive trips and training courses require an advance deposit before the spot in confirmed, which may not be refunded in the case of customer cancellation depending on the timing of the cancellation. This is especially true of trips that require prearranged and prepaid logistics such as ferry or lodging, like in the case of island excursions. 

Deposits and prepay requirements will be stated when a trip is offered, and payment of this amount will be required before the trip reservation is confirmed. Basic rules, unless modified in a specific trip/course description:

Island Trips: Island trips are the most fun, and also represent the highest level of planning and investment of time, logistics and money on our part. If a thick slice of "life" happens and forces you to cancel your trip, cancellation fees are as follows (unless there is a wait list and another diver ready and able to fill the spot):

• Cancel 47 hours or less in advance of event start/departure (must pay 100% of total trip fees)

• Cancel 2-7 days in advance of event start (must forfeit the designated deposit amount, usually JPY 20-30,000).

Weekend Trips: For non-island trips where an overnight stay and meals were reserved, there will be cancellation fee depending on the location and timing. At Osezaki, we have three days prior to check-in to cancel. At other locations (such as IOP) we begin to occur cancellation fees a week in advance, so we must pass on this timing. Other locations will be highlighted in the event description/announcement if they have unique cancellation timing/fees. As a rule of thumb: 

• Cancel on the day of an event (must pay 100% total weekend fees)

• Cancel 47 hours or less in advance of event start (must pay 75-100% of total weekend fees)

• Cancel 2-7 days in advance of event start (must pay 50% of total weekend fees)

Day trips: In the case of shore diving, there are generally NOT trip cancellation fees, unless specifically noted for a dive event. In the case of boat diving, there will be fees on the following schedule:

• Cancel on the day of an event (must pay 100% total weekend fees)

• Cancel 47 hours or less in advance of event start (must pay 50-100% of total weekend fees)

• Cancel 2-7 days in advance of event start (must pay 50% of total weekend fees)

"Partial" Event Cancellations: While on a day trip or weekend event, a diver will feel tired, ill or have to suddenly leave before the dives, stay, and or meals of the trip have been finished. In such an unfortunate occurrence, the diver will unfortunately be responsible for 100% of the costs for the day or weekend trip. This includes, cancelling one of two boat/shore dives or leaving a day early on a weekend trip.

Equipment cancellations: Equipment cancellation fees generally fit into the scenarios above, except in the case of day trips of shore diving. While cancelling shore diving in the last 24 hours does not incur dive fee cancellations, there will be rental gear cancellation fees for gear that was reserved and arranged: 

• Cancel 24 hours or less in advance of a day trip shore dive (must pay 100% total gear rental fees)

• Cancel 25-48 hours in advance of day trip shore dive (must pay 50% of gear rental fees)

Loss/Damage of Scuba Equipment 
If a customer loses or damages equipment borrowed or rented from the dive center, that customer will be liable for any replacement fee levied by the dive center. These fees are generally quite reasonable.If a diver loses or damages equipment belonging to Discovery Divers Tokyo, that diver will pay a replacement price, or may be given the option to “go shopping” and find a replacement item from a discount scuba outlet.

Risks 
Scuba diving and dive training by its very nature is a risky activity. As divers, we enter a beautiful, but potentially hostile environment that requires life support equipment to survive. Participants who join diving trips and training must take responsibility for making the choice to participate in these activities with the understanding that there is risk to life and limb anytime you are near, in, or under water with or without scuba equipment.