You can not cross over to the island and go up to the other trails near the cabin at high tide.
The trail goes up and down towards the river turns down to the small island, at low tide it's possible to cross the island and go up to the trail along the cabins. but avoid the island near the river flow, the stream can be quite fast, and could be dangerous. this trail is not suitable for mountain biking or running, as it's so close to the river, at least if you haven't been there before.
You can walk up a steep section of trail, it's quite narrow too, from the rock bottom to or from the path that runs between the cabins.