The good thing about the Galapagos is that you can travel here all year round! There are optimal seasons depending on what is important to you.
For example, for diving and snorkeling. When the water is as clear as possible. It is in July.
July-August the nesting season for most Galapagos birds. And the highest chances of seeing chicks. Marine iguanas breed in May-June. And small iguanas can seen in late summer. July-August the time of mating sea lions, which were our main goal.

But if you have other goals. For example, swimming in the sea for hours. Then December is better. At this time the water is the warmest. And if you want to see an abundance of colorful marine iguanas. You need the months from January to March. Because this is the sexual period activity. And males are painted bright green and reddish pink to attract females. During the period from January to May. (which is also the Dodge season). There is vegetation and rain. In the dry season the landscapes are more desolate. But the weather is clearer and warmer. The waves are much smaller from January to May. And in July-August they reach their peak. But in the dry season, there are way fewer tourists on the islands. According to statistics. Here then you can see the animals are active in some months.