A 'boundless swimming pool' typically refers to a swimming pool that appears to have no edges or boundaries, often giving the illusion of being part of a larger body of water, like the ocean. This type of design is often found in high-end resorts or luxury hotels. The term 'Tian tai' likely refers to a location or a specific project named 'Tian Tai', possibly a resort or a residential area with such a pool. Pictures of such pools often showcase stunning views and architectural innovation.