The Isle of Coll has several beautiful beaches but none of this is signposted. With a navigation system on your mobile phone, it is much better to find.
Like most of the beaches at the Isle of Coll Hogh Beach is much better accessible at low tide.
The best chance of great weather is usually from April to the beginning of July. From mid-July to August there is a higher chance of rain. September is also a good month. Coll is very busy in July and August. In the peak season, it is more difficult to get an accommodation.
I visited the island in late June and I was very lucky to get showed such a huge variety of wildflowers.
A wide variety of different wildflowers can be seen from May to September. The best months are June and July. However, it is not possible to see all of them on one visit. The best chance for pleasant weather is usually from April to the beginning of July. From mid-July to August it rains more frequently.
Our guide Luke, a marine biologist, explained that young sharks disappear as soon as you get into the water. It only makes sense to snorkel with older and bigger ones.
The season starts middle of June until September. The highest chance for a sighting is also the peak season on the Hebrides in July and August. Anyway, no guarantee at all. I booked a four-day trip to increase the chance for snorkeling with one and I only saw a young one from the boat. One guy had booked a trip for the third time and our three meters tall shark was his first one. You need the right conditions and also a lot of luck!!
I'd recommend August now. This is also the month when the shark festival takes place at one weekend.